Đề tài Statnamic testing of piles in clay

istances from the chamber centre line. For each bed the accelerometers were positioned at different heights and radial locations from the pile with the main aim of monitoring the soil accelerations during rapid load pile tests. The locations of pore water pressure transducers and accelerometers for Bed 1 to Bed 5 are shown in Figure (4.1) to Figure (4.5). In these figures, a pore water pressure transducer is denoted by PW and an accelerometer by AC. In these figures, the reference position of a transducer is also given and denoted by the letter C with a number such as C12, C3 etc. 4.3 Constant rate of penetration tests (CRP tests) To get a better understanding of response of clay at different shearing velocities, a wide range of rates for CRP tests was used. The details of CRP tests from Bed 1 to Bed 5 are shown in Table 4.1 to Table 4.5. The tests carried out at the rate of 0.01 mm/s were considered as the static tests which provided the pile static capacity Chapter 4 Testing Programme 104 benchmark. Due to the local consolidation developed in the vicinity of the pile from test to test the CRP test with the rate of 0.01 mm/s was repeated after several quick load tests. In the testing programme of Bed 1 to Bed 5 (Tables 4.1 to 4.5), the target penetration rates such as 100 mm/s or 200 mm/s were the input values for the computer which controlled the driving actuator system. However, the actual velocities were slightly different from the target values. In reality, the pile velocity under a CRP test developed from zero to a value near the target velocity and the real velocities were used in the data analyses. 4.4 Statnamic tests (STN tests) In order to replicate a real field statnamic test, a loading pulse with a period of 200 ms was applied to the pile top. Additionally, in order to investigate the effect of a long pulse load during STN tests on the pile's dynamic capacity some STN tests with a longer loading period were also used. Similar to the target velocities for CRP tests, the target peak loads of STN tests in Table 4.1 to Table 4.5 were the input values for the computer which controlled the actuator. The real peak loads were smaller than the target peak loads and the differences between them depended on the clay stiffness. In data analyses, the real values which were measured directly by the actuator load cell were used. A range of peak loads for STN tests was used which depended on the pile dynamic capacity. If the peak load of a STN test was too low compared with the pile's dynamic capacity, pile settlements were small or zero. On the other hand, if the peak load was too high a large pile settlement occurred which reduced the number of tests which could be carried out in a clay bed. For that reason, the peak loads were generally chosen in a range such that settlement under one test was from about 3 mm to 7 mm. However, in order to extend the available data, a number of STN tests were carried out with settlements outside of this range. Chapter 4 Testing Programme 105 4.5 Maintained load (ML) tests Tests on the first bed revealed that the servo control system was not sufficiently stable for maintained load testing. For that reason, from the Bed 2 onwards the actuator which supplied load for 1-D consolidation was used for the ML tests. It was found that there was hysteresis under long term loads of the strain gauge bonds on the aluminium making up the pile skin load cell and as a result a new skin load cell was manufactured after Bed 3. ML tests were not conducted for Bed 4 as it was felt that this might cause degradation of the strain gauges again. The ML tests were carried out, as described in Section 3.9.3, with the aim of providing further information about the static pile capacity in conjunction with CRP tests . Chapter 4 Testing Programme 106 Table 4.1 Testing programme for Bed 1 Table 4.2 Testing programme for Bed 2 Testing Test Type 3-D Target Comment/ Date of number reference consolidation penetration peak Time pulse purpose test pressure (kPa) rate (mm/s) load (kN) (ms) 1 B1/1/CRP-0.01 CRP 280 0.01 Static benchmark 10h-2/12/03 2 B1/2/CRP-100 CRP 280 100 4h-3/12/03 3 B1/3/STN-10 STN 280 10 200 4h-4/12/03 4 B1/4/STN-15 STN 280 15 200 4h-5/12/03 5 B1/5/CRP-0.01 CRP 280 0.01 Static benchmark 11h-8/12/03 6 B1/6/STN-16 STN 280 16 200 4h-8/12/03 7 B1/7/CRP-25 CRP 280 25 11h-9/12/03 8 B1/8/CRP-200 CRP 280 200 4h-9/12/03 9 B1/9/CRP-10 CRP 280 10 11h-10/12/03 10 B1/10/STN-17 STN 280 17 200 3h-10/12/04 11 B1/11/MLT MLT 280 Not finished 11/12/2003 12 B1/12/CRP-0.01 CRP 280 0.01 Static benchmark 12h-12/12/03 STN tests Testing Test Type 3-D Target Comment/ Date of number reference consolidation penetration peak Time pulse purpose test pressure (kPa) rate (mm/s) load (kN) (ms) 1 B2/1/CRP-0.01 CRP 280 0.01 Static benchmark 4h-1/4/04 2 B2/2/CRP-10 CRP 280 10 5h-2/4/04 3 B2/3/CRP-50 CRP 280 50 5h-5/4/04 4 B2/4/CRP-100 CRP 280 100 4h-6/4/04 5 B2/5/CRP-150 CRP 280 150 3h-7/4/04 6 B2/6/CRP-200 CRP 280 200 11h-8/4/04 7 B2/7/CRP-0.01 CRP 280 0.01 Static benchmark 3h-8/4/04 8 B2/8/STN-30 STN 280 30 200 3h-14/4/04 9 B2/9/STN-35 STN 280 35 200 3h-15/4/04 10 B2/10/STN-38 STN 280 38 200 3h-16/4/04 11 B2/11/CRP-300 CRP 280 300 3h-19/4/04 12 B2/12/CRP-0.01 CRP 280 0.01 Static benchmark 12h-20/4/04 13 B2/13/MLT MLT 280 Static benchmark 26/04/2004 14 B2/14/MLT MLT 280 Static benchmark 27,28/4/04 15 B2/15/MLT MLT 280 Static benchmark 29/04/2004 16 B2/16/CRP-0.01 CRP 280 0.01 Static benchmark 2h-30/4/04 17 B2/17/STN-38 STN 280 38 200 3h-4/5/04 18 B2/18/CRP-400 CRP 280 400 3h-5/5/04 19 B2/19/CRP-150 CRP 280 150 3h-6/5/04 20 B2/20/CRP-0.01 CRP 280 0.01 Static benchmark 2h-7/5/04 STN tests Chapter 4 Testing Programme 107 Table 4.3 Testing programme for Bed 3 Testing Test Type 3-D Target Comment/ Date of number reference consolidation penetration peak Time pulse purpose test pressure (kPa) rate (mm/s) load (kN) (ms) 1 B3/1/CRP-0.01 CRP 280 0.01 Static benchmark 3h-26/7/04 2 B3/2/CRP-10 CRP 280 10 3h-27/7/04 3 B3/3/CRP-25 CRP 280 25 3h-28/7/04 4 B3/4/CRP-50 CRP 280 50 3h-29/7/04 5 B3/5/CRP-100 CRP 280 100 3h-30/7/04 6 B3/6/CRP-0.01 CRP 280 0.01 Static benchmark 3h-2/8/04 7 B3/7/CRP-150 CRP 280 150 3h-3/8/04 8 B3/8/STN-30 STN 280 30 200 3h-4/8/04 9 B3/9/CRP-200 CRP 280 200 3h-5/8/04 10 B3/10/STN-35 STN 280 35 200 3h-6/8/04 11 B3/11/CRP-10 CRP 280 10 3h-9/8/04 12 B3/12/CRP-250 CRP 280 250 3h-10/8/04 13 B3/13/STN-38 STN 280 38 200 3h-11/8/04 14 B3/14/CRP-5 CRP 280 5 3h-12/8/04 15 B3/15/CRP-0.01 CRP 280 0.01 Static benchmark 3h-13/8/04 16 B3/16/CRP-300 CRP 280 300 3h-16/8/04 17 B3/17/CRP-200 CRP 280 200 3h-17/8/04 18 B3/18/CRP-100 CRP 280 100 3h-18/8/04 19 B3/19/CRP-1 CRP 280 1 3h-19/8/04 20 B3/20/CRP-0.5 CRP 280 0.5 3h-20/8/04 21 B3/21/CRP-0.01 CRP 280 0.01 Static benchmark 3h-23/8/04 22 B3/22/MLT MLT 280 Static benchmark 25,26/8/04 23 B3/23/MLT MLT 280 Static benchmark 27/12/8/04 STN tests Chapter 4 Testing Programme 108 Table 4.4 Testing programme for Bed 4 Testing Test Type 3-D Target Comment/ Date of number reference consolidation penetration peak Time pulse purpose test pressure (kPa) rate (mm/s) load (kN) (ms) 1 B4/1/CRP-0.01 CRP 280 0.01 Static benchmark 3h-18/11/04 2 B4/2/CRP-100 CRP 280 100 3h-19/11/04 3 B4/3/CRP-150 CRP 280 150 3h-22/11/04 4 B4/4/CRP-200 CRP 280 200 2h-23/11/04 5 B4/5/CRP-0.01 CRP 280 0.01 Static benchmark 1h-24/11/04 6 B4/6/STN-30 STN 280 30 200 3h-25/11/04 7 B4/7/STN-30 STN 280 30 200 10h-26/11/04 8 B4/8/CRP-0.01 CRP 280 0.01 Static benchmark 3h-26/11/04 9 B4/9/CRP-300 CRP 280 300 1h-29/11/04 10 B4/10/CRP-0.01 CRP 280 0.01 Static benchmark 10h-30/11/04 11 B4/11/STN-35 STN 280 35 200 3h-30/11/04 12 B4/12/CRP-400 CRP 280 400 11h-1/12/04 13 B4/13/CRP-0.01 CRP 280 0.01 Static benchmark 3h-2/12/04 14 B4/14/CRP-50 CRP 280 50 2h-3/12/04 15 B4/15/CRP-25 CRP 280 25 12h-6/12/04 16 B4/16/CRP-125 CRP 280 125 10h-7/12/04 17 B4/17/CRP-0.01 CRP 280 0.01 Static benchmark 3h-7/12/04 18 B4/18/CRP-100 CRP 400 100 10h-10/12/04 19 B4/19/CRP-0.01 CRP 400 0.01 Static benchmark 3h-10/12/04 20 B4/20/CRP-150 CRP 400 150 10h-13/12/04 21 B4/21/STN-35 STN 400 35 200 2h-13/12/04 22 B4/22/CRP-0.01 CRP 400 0.01 3h-14/12/04 23 B4/23/STN-38 STN 400 38 200 11h-14/12/04 24 B4/24/STN-40 STN 400 40 200 10h-15/12/04 25 B4/25/CRP-75 CRP 400 75 12h-16/12/04 26 B4/26/CRP-50 CRP 400 50 3h-16/12/04 27 B4/27/CRP-0.01 CRP 400 0.01 Static benchmark 10h-17/12/04 28 B4/28/CRP-25 CRP 400 25 3h-17/12/04 29 B4/29/STN-28 STN 400 38 400 12h-20/12/04 STN tests Chapter 4 Testing Programme 109 Table 4.5 Testing programme for Bed 5 Testing Test Type 3-D Target Comment/ Date of number reference consolidation penetration peak Time pulse purpose test pressure (kPa) rate (mm/s) load (kN) (ms) 1 B5/1/CRP-0.01 CRP 240 0.01 Static benchmark 10h-14/3/05 2 B5/2/CRP-100 CRP 240 100 3h-14/3/05 3 B5/3/STN-15 STN 240 15 200 10h-15/3/05 4 B5/4/CRP-75 CRP 240 75 12h-15/3/05 5 B5/5/CRP-0.01 CRP 240 0.01 Static benchmark 5h-15/3/05 6 B5/6/STN-15 STN 240 15 200 10h-16/3/05 7 B5/7/STN-20 STN 240 20 200 11h-16/3/05 8 B5/8/CRP-150 CRP 240 150 2h-16/3/05 9 B5/9/CRP-0.01 CRP 240 0.01 Static benchmark 5h-16/3/05 10 B5/10/CRP-100 CRP 240 100 10h-17/3/05 11 B5/11/CRP-0.01 CRP 240 0.01 Static benchmark 10h-18/3/05 12 B5/12/CRP-0.01 CRP 280 0.01 Static benchmark 10h30-18/3/05 13 B5/13/CRP-0.01 CRP 280 0.01 Static benchmark 10h-21/3/05 14 B5/14/CRP-100 CRP 280 100 4h-21/3/05 15 B5/15/CRP-0.01 CRP 280 0.01 Static benchmark 10h-22/3/05 16 B5/16/CRP-200 CRP 280 200 4h-22/3/05 17 B5/17/STN-25 STN 280 25 200 4h-23/3/05 18 B5/18/CRP-0.01 CRP 280 0.01 Static benchmark 4h-23/3/05 19 B5/19/CRP-500 CRP 280 500 10h-24/3/05 20 B5/20/CRP-0.01 CRP 340 0.01 Static benchmark 10h-29/3/05 21 B5/21/CRP-100 CRP 340 100 3h30-29/3/05 22 B5/22/CRP-300 CRP 340 300 10h-30/3/05 23 B5/23/CRP-200 CRP 340 200 3h-30/3/05 24 B5/24/CRP-0.01 CRP 340 0.01 Static benchmark 10h-31/3/05 25 B5/25/CRP-150 CRP 340 150 3h-31/3/05 26 B5/26/STN-30 STN 340 30 200 10h-1/4/05 27 B5/27/STN-32 STN 340 32 200 3h-1/4/05 28 B5/28/STN-35 STN 340 35 200 10h-4/4/05 29 B5/29/STN-34 STN 340 34 400 3h-4/4/05 30 B5/30/CRP-0.01 CRP 340 0.01 Static benchmark 10h-5/4/05 31 B5/31/CRP-125 CRP 340 125 3h-5/4/05 32 B5/32/CRP-50 CRP 340 50 11h-6/4/05 33 B5/33/CRP-10 CRP 340 10 3h-6/4/05 34 B5/34/CRP-0.01 CRP 340 0.01 Static benchmark 12h-7/4/05 35 B5/35/MLT MLT 340 Static benchmark 10h-11/4/05 36 B5/36/MLT MLT 340 Static benchmark 10h-12/4/05 STN tests Chapter 4 Testing Programme 110 Figure 4.1 Transducer arrangement for Bed 1 (All dimensions in mm) (PW – Pore water pressure; AC – Accelerometer) (The number next to the transducer is height above the base) Figure 4.2 Transducer arrangement for Bed 2 (All dimensions in mm) (PW – Pore water pressure; AC – Accelerometer) (The number next to the transducer is height above the base) W 185350 295 240 130 75 13075 185 240 295 350 E druck druck Final boundary final level 14 0 70 12 0 initial level 450 Ac Ac 490 200 PW of sample 790 1,0 60 500 PW S295N 185 75 130 240 350 of sample Final boundary druck 70 12 0 level initial druck final level 14 0 750 PW 350 PW 390 PW 410 PW in pile Ac 730 PWmo ve me nt ra ng e C17 C18 C5 C1 C2 C3 C4 C7 C6 PW C8 770 W 185350 295 240 130 75 13075 185 240 295 350 E kulite Kulite Final boundary final level 1 5 0 70 12 0 initial level 750 PW 743 PW of sample 790 1,0 6 0 470 PW S295N 185 75 130 240 350 1 ,0 60 790 of sample Final boundary kulite 70 12 0 level initial kulite final level 15 0 250 PW 475 PW in pile Ac 485 PW mo ve me nt ra ng e C1 C2 C4 C5 C7 C6 PW C8 640 PW 743 C3 AC 455 C17 AC 485 C18 Height above the base Radial distance from the centre Chapter 4 Testing Programme 111 Figure 4.3 Transducer arrangement for Bed 3 (All dimensions in mm) (PW – Pore water pressure; AC – Accelerometer) (The number next to the transducer is height above the base) NW 170 120 75 12075 170 SE druck druck Final boundary final level 17 0 70 12 0 initial level 100 Ac Ac 150 of sample 790 1,0 60 in pile Ac 1,0 60 17 0 EW 240240350 295 185 130 7575 130 185 295 350 PW 410 500 Ac 450 Ac 450 12 0 druck level final PW 350 in pile level initial Ac 390 PW PW druck 70 790 of sample Final boundary 17 0 1 ,0 60 35024013075185N 295 S level final druck initial level 70 druck 750 PW 12 0 mo ve me nt ra ng e PW 730PW 770 790 Final boundary of sample Ac 490 450 Ac Ac 150 150 PW Ac in pile c4 c5 c1 c7 c2 c3 c6 c8 c17 c24 c25 c23 c18 c21 c22 Chapter 4 Testing Programme 112 Figure 4.4 Transducer arrangement for Bed 4 (All dimensions in mm) (PW – Pore water pressure; AC – Accelerometer) (The number next to the transducer is height above the base) NW 170 120 12075 170 SE druck druck Final boundary final level 17 0 70 18 5 initial level of sample 790 1,0 60 in pile Ac 1,0 60 17 0 EW 240240350 295 185 130 7575 130 185 295 350 ac 400 495 pw 403 pw 384 478 Ac 18 5 druck level final PW 85 in pile level initial Ac 445 ac PW druck 70 790 of sample Final boundary 17 0 1,0 60 35024013075185N 295 S level final druck initial level 70 druck668 ac 18 5 mo ve me nt ra n g e PW 638 790 Final boundary of sample Ac 484 442 Ac 745 PW Ac in pile C1 C7 c6 C8 C4 c3 75 C21 C17 C22 C23 C18 C24 Chapter 4 Testing Programme 113 Figure 4.5 Transducer arrangement for Bed 5 (All dimensions in mm) (PW – Pore water pressure; AC – Accelerometer) (The number next to the transducer is height above the base) 1,0 60 17 5 EW 240240350 295 185 130 7575 130 185 295 350 ac 400 495 pw 384 300 Ac 18 5 druck level final PW 85 in pile level initial Ac PW druck 70 790 of sample Final boundary 17 5 1,0 60 35024013075185N 295 S level final druck initial level 70 druck668 ac 18 5 mo ve me nt ra ng e 790 Final boundary of sample Ac 484 442 Ac Ac in pile C1 C7 C2 C18 C17 C24 C21 C22 620 pw C4 Chapter 5 Bed properties 114 CHAPTER 5 BED PROPERTIES 5.1 Introduction It was desirable to produce consistent soil properties from bed to bed. However, differences were inevitable and attempts have been made to minimise these. Three aspects of bed consolidation were monitored which were: - consolidation time period; - settlements and equivalent volume changes of the bed; - pore water pressures at different locations in the beds. When the tests were completed, moisture contents and shear strengths were determined at different locations in the beds. The shear strengths were determined by conventional unconsolidated undrained triaxial tests on undisturbed thin wall tube samples and hand vane tests in the clay beds. It was interesting to note from visual observation and moisture content data that considerable local consolidation developed in the thin zone around the pile shaft and at the pile tip. This chapter will provide details of the soil properties of Beds 1 to 5 to not only provide information for data analyses but also to give information, to some extent, about the mechanism of the load transfer during tests which led to local consolidation around pile shaft and pile tip. 5.2 Clay bed 1-D consolidation 1-D consolidation for Beds 1 to 4 went through three stages: - Vertical stress 65 kPa for about 3 hours; - Vertical stress 105 kPa for about 3 days; - finally, vertical stress of 280 kPa until completion of 1-D consolidation Bed 5, went through the same consolidation procedure except that the bed was subjected to only 240 kPa for the final step. The purpose of the two first steps was to Chapter 5 Bed properties 115 create an initial strength for the clay bed before being subjected to a relatively large pressure increase. Therefore, the soft clay slurry did not get squeezed out with the expelled water under a large pressure increase. Additionally, the three stage loading allowed the monitoring of the volume of expelled water which was collected by two volume change tanks which needed to be emptied regularly. 1-D consolidation was terminated when the degree of consolidation at the mid height of the bed was greater than about 40% or 47% (Brown 2004) for 1-D consolidation pressures of 280kPa and 240kPa respectively and when the bed height was reduced to about 1100 mm which was suitable for the triaxial chamber. This ensured that: - subsequent isotropic triaxial consolidation only generated small volume changes which could be accommodated by the top membrane. As mentioned in Section 3.4.5 the membrane could only accommodate a vertical movement of 100 mm. - clay beds had enough strength to stand alone when changing from 1-D to isotropic triaxial consolidation. The settlements of the clay beds under 1-D consolidation are shown in Figure 5.1 in which the initial settlements shown at zero time were the settlements during the 65 and 105 kPa pressure stages, and after that settlements were for 280 kPa for Beds 1 to 4 and 240 kPa for Bed 5. Although the same 1-D consolidation procedure was used for Beds 1 to 4, the settlement – time lines were not identical. Beds 1, 2 and 4 achieved settlements of about 453 mm. However, only Beds 1 and 4 attained this settlement at the same time (about 340 hours of consolidation under 280 kPa) whereas Bed 2 reached a value of 453 mm after a much longer time, 570 hours. For Bed 3 a much lower settlement of 413 mm was achieved even though the settlement curve had reached the asymptotical trend. These differences could be due to the following reasons: ♦ There was a power cut for about 2 days during the consolidation of Bed 2 making the consolidation time much longer than the others; ♦ The top drainage conditions were slightly different from bed to bed. It was desirable that water passed through a de-aired filter placed between the clay bed and the top plate and then out to the volume change tank through two hoses which were Chapter 5 Bed properties 116 connected to the plate. Two o-rings were used to prevent water passing in between the top plate and the consolidometer (Figure 3.10). However, leakage occurred between the top plate and the consolidometer for Bed 1 and it altered the drainage conditions. A large volume of 81.00dm3 water leaked between the plate and the consolidometer compared with the total water of 94.02dm3 expelled from the top. It can be seen from Table 5.1 that only slightly more water was expelled from the bottom than from the top except for Bed 1 and Bed 2. As already mentioned there was a leak for Bed 1 and there was more water expelled from the top than from the bottom. On the other hand, for Bed 2 more water came from the bottom than from the top. This could be due to the top filter not being deaired thoroughly for Bed 2, thus hindering drainage. ♦ The initial clay bed heights were different. Although the same amount of material was used to mix slurry for Beds 1 to 5 it was inevitable that the final amount of slurry which was pumped into the consolidometer was different due to the loss of material during the mixing and pumping processes. ♦ The use of materials was not consistent from bed to bed. Only materials of Bed 1 and 2 were consistent. From Bed 3 onwards a mixture of two kaolins, which were supplied by EEC international Ltd and left after Bed 2, and a new one which was supplied by Imerys Mineral Ltd was used. It was thought that the kaolins would be identical since no differences of the kaolins were claimed by the two companies, so the mixtures of kaolin were not controlled during the preparation of the slurry. During mixing it was found that the two kaolins were not identical and the old slurry was slightly more ‘sticky’ than the new one. However, liquid and plastic limits are not available to confirm this conclusion. In addition, a grade 4 silt was used for Beds 1 to 2, but the company discontinued the supply of this silt and from Bed 3 onwards grade 3 silt was mixed with grade 5 silt as a replacement for the grade 4 silt. The 1-D consolidation was monitored by buried pore water transducers at different locations in the clay beds. The data from these transducers for Beds 1 to 5 are plotted in Figures 5.2 to 5.6 assuming that the variation between values measured at two adjacent transducers is linear. The measured pore water pressure dissipations at the mid height of the clay beds indicated that Beds 1 to 5 finished 1-D consolidation at 89.9%, 52.1%, 86.7%, 68.6%, and 87.7% respectively. No clear explanation can be forward for the low degree of consolidation of Bed 2 and 4 even though their Chapter 5 Bed properties 117 settlement curves had reached the asymptotical trend. Fortunately, the following stage of consolidation, isotropic triaxial consolidation, was more consistent for Beds 1 to 5. 5.3 Clay bed isotropic triaxial consolidation Once the 1-D consolidation stage finished, the pressure was reduced gradually to zero. The consolidometer was then removed to leave the clay sample self-supporting for a short period before initiating isotropic triaxial consolidation. The pile was installed in the clay bed before the triaxial consolidation for Beds 2 to 5. With Bed 1, due to the pile not being ready at the time of the change over, it was installed in the clay bed after 3 weeks of isotropic triaxial consolidation. Prior to applying the isotropic triaxial consolidation pressure, the rods which were used to position buried transducers were removed leaving the transducers to move freely during isotropic triaxial consolidation. For this reason, the final positions of transducers were measured when dissecting the clay beds. These are shown in Figures 5.7 to 5.11. Tests were carried out after a substantial degree of isotropic triaxial consolidation, defined as the ratio of effective stress to the total applied stress at the mid height, was achieved. The degrees of consolidation for the first tests of Beds 1 to 5 were 86.2%, 88.6%, 81.6%, 90.5%, and 94.8% respectively. During the testing programme, the consolidation continued and the degrees of consolidation for the final tests for the 5 beds were 88.4%, 92.1%, 88.3%, 90.3%, and 96.8% (Table 5.2) respectively. It should be noted that a number of levels of isotropic triaxial consolidation were used for Bed 4 and Bed 5. In general, it can be seen that the final degrees of consolidation for triaxial conditions were more consistent than for the 1-D consolidation. 5.4 Performance of the calibration chamber during the pile load tests The loading frame was connected to the top of the chamber body via connections at the centre and at the rim of the top plate of Bed 1 and 2. However, it was found that these connections caused a deflection for the pile top plate and as a result the top cell Chapter 5 Bed properties 118 pressure fluctuated considerably during rapid pile load tests. For that reason, from Bed 3 onwards the connections between the loading frame and the top plate were strengthened by two angle section beams and the connection at the centre of the top plate was removed. The new connections reduced significantly the fluctuations of the top cell and side cell pressures (Figure 5.12). The results in Figure 5.12 show that before the modification the top cell pressure dropped from 280kPa to 225kPa during a CRP test at the rate of 200mm/s whereas after the modification it only dropped from 280kPa to 255kPa. Although the fluctuations of the top and side cell chamber body pressures were improved it was still thought that these fluctuations could have an effect on the pore water pressures in the clay beds. To examine the influence of the changes of the top cell chamber body pressure on the pore water pressures in the clay beds a simple test was carried out for Bed 4 when the pile load test programme had finished. During that test the pore water pressures in the clay bed were measured while the top cell pressure was suddenly reduced from 400kPa to 200kPa. The results are shown in Figure 5.13. It can be seen that only the pore pressure of channel 6 which was located about 350mm below the top surface of the clay bed was influenced and it dropped from 3.4kPa to –18.9kPa. However, the changes took place over a period of about 4500ms (from 2500ms to 7000ms) whereas a rapid pile load test normally occurred from 140ms with the shearing velocity of 50mm/s to 35ms with the shearing velocity of 200mm/s. For that reason, the changes occurring over a period of 200ms are considered and hence Figure 5.13 becomes Figure 5.14. If the changes over a period of 200ms are considered the influence of the drop of the top cell pressure on the pore pressures in the clay bed reduced significantly. Figure 5.14 shows that over a period of 200ms the top cell pressure dropped from 400kPa to 298kPa and this change was more significant than that during a rapid pile load test, but the changes of pore pressures in the clay bed were negligible. Chapter 5 Bed properties 119 5.5 Bed properties after the testing programme After completing the testing programme, the isotropic triaxial consolidation pressure was reduced gradually to zero and the calibration chamber was dismantled. The clay bed properties were determined at different locations, as described in Section 3.10 by: - hand vane tests - thin wall tube sampling for unconsolidated undrained triaxial tests - sampling for moisture contents. The results from the hand vane tests in Beds 1 to 5 are shown in Tables 5.3 to 5.7. It can be seen from the results that in the vertical direction the lowest shear strength was at the top of the clay beds and the strength increased gradually over a distance of about 400 mm towards the middle of the clay beds. This could be due to the use of two steel rings for the top plate of the chamber (Figure 3.15). The vertical pressure during isotropic triaxial consolidation was not uniformly distributed on the surface of the clay beds due to the use of these two relatively bulky rings. Owing to the high isotropic triaxial consolidation pressures of up to 400 kPa, leaks could easily occur between the top plate and its attached membrane. Thus, no modification was made to the dimensions of these rings. In the radial direction, there were no apparent differences in shear strength except for a narrow zone of about one and a half pile diameters from the pile shaft where the soil was heavily overconsolidated and its strength was much higher. Due to a visible difference between a thin zone around the pile shaft and the rest, hand vane tests were carried out for this zone for Beds 4 and 5 (Tables 5.6 and 5.7). These tests were conducted in the horizontal direction since the thin zone and the dimension of the hand vane did not allow tests in the vertical direction with the pile still being in place. To carry out horizontal direction hand vane tests soil around the pile was trimmed to a radial distance of about 100mm which allowed the vane blades to get into the soil zone near the pile shaft. Due to the concern about soil anisotropy both horizontal and vertical hand vane tests were carried out at a number of locations and the results were found to be identical. Chapter 5 Bed properties 120 Beds 1 to 3 had the same history of consolidation. However, Bed 3 was softer than the others and there was no clear explanation for this. Bed 4 was strongest as it was subjected to isotropic triaxial consolidation at 400 kPa. Comparison of the shear strength distribution of Bed 4 with that of Beds 1 and 2 indicated that isotropic triaxial consolidation did not influence the top zone of about 300 mm as shear strengths in these zones were similar for the 3 clay beds (1, 2, and 4). The same phenomenon was observed for Bed 5. This bed underwent 1-D consolidation at 240 kPa and isotropic triaxial consolidation at 340 kPa. The shear strengths in Bed 5 were larger than those of Beds 1 and 2 in the central zone of the clay bed but were smaller at the top of the bed. This suggests that triaxial consolidation may have been hampered near the top resulting in lower effective stress, and hence strength. When dissecting the beds, samples were taken for moisture content determinations (Tables 5.8 to 5.12). The thin zone below the pile tip was better quantified by the moisture contents as it was impossible to determine shear strengths at different distances from the pile tip (Tables 5.11 & 5.12). It was inferred from the moisture contents in the pile tip zone that the soil strength here was much higher than in the surrounding areas. The moisture contents increased from the pile tip to a more average value over a distance of about two and a half pile radii (105 mm). Similarly, the stronger zone around the pile shaft was about two to three pile radii. Samples were also taken for conventional unconsolidated undrained triaxial tests and their results are shown in Table 5.13. Three to four samples were taken for each bed at a level of about 550 mm from the bottom plate. The shear strengths determined from the triaxial tests were relatively consistent with those from the hand vane tests. The shear strengths of Bed 4 from the triaxial tests were slightly lower than those of Beds 1 and 2. This was thought that its samples were taken at a higher level in the bed. On the other hand the shear strengths of Bed 3 from the triaxial tests were higher than the other beds. This was thought that these samples were taken at a lower level in the bed or technical mistakes would occur during the triaxial tests being carried out. Chapter 5 Bed properties 121 Table 5.1 Volume of water expelled during 1-D consolidation Table 5.2 Isotropic triaxial consolidation degrees of Beds 1 to 5 Bed number Top Bottom Top Bottom Top Bottom Top Bottom Top Bottom The water expelled during 65 kPa 1-D 3.34 1.50 2.81 5.95 2.64 4.51 11.59 0.00 19.30 28.75 consolidation (dm3) The water expelled during 105 kPa 1-D 36.87 29.19 5.69 30.26 10.30 16.84 12.08 24.12 15.91 17.15 consolidation (dm3) The water expelled during 280 (240) kPa 53.80 57.35 49.66 105.80 64.44 58.55 43.78 44.30 60.50 66.83 1-D consolidation (dm3) water of 3 stages (dm3) 94.02 88.04 58.15 142.01 77.38 79.90 67.46 68.42 95.71 112.73 Total top & bottom (dm3) From From From From From 5 182.06 200.16 157.28 135.87 208.44 1 2 3 4 Bed number 1th Final 1th Final 1th Final 1th Final 1th Final Degree of isotropic consolidation at the 86.2 88.4 88.6 92.1 81.6 88.3 90.5 90.3 94.8 96.8 middle of the sample Total horizontal consolidation 280 280 280 280 280 280 280 400 240 340 stress Horizontal effective stress at the middle 241.3 247.6 248.0 258.0 228.5 247.2 253.4 361.1 227.6 329.0 of the sample TestsTests Tests Tests Tests 51 2 3 4 Chapter 5 Bed properties 122 Table 5.3 Undrained shear strengths of Bed 1 determined by hand vane tests Distance Distance from the centre from the base North West South East Average of the chamber of the chamber mm mm kPa kPa kPa kPa kPa 100 900 43.7 43.1 41.7 41.7 200 900 45.8 45.8 41.1 43.1 43.3 300 900 43.1 48.5 41.7 40.4 100 800 44.4 43.1 45.8 44.4 200 800 45.8 49.1 43.1 45.8 45.4 300 800 45.8 45.8 44.4 47.1 100 700 45.8 48.5 49.1 47.1 200 700 48.5 48.5 45.8 51.1 48.4 300 700 49.8 51.1 47.1 48.5 100 600 53.8 51.1 49.8 51.1 200 600 48.5 47.1 45.8 49.8 49.7 300 600 51.1 47.1 52.5 48.5 100 500 52.5 52.5 52.5 59.2 200 500 52.5 53.8 54.5 53.8 52.6 300 500 48.5 49.8 51.1 49.8 100 400 53.2 51.1 53.8 51.1 200 400 53.8 51.1 51.1 51.1 51.4 300 400 48.5 50.5 49.8 51.8 100 300 53.2 51.1 53.8 52.5 200 300 54.5 49.8 47.1 51.1 51.4 300 300 51.1 49.8 51.1 51.1 100 200 55.2 56.5 56.5 59.2 200 200 48.5 51.1 48.5 49.8 51.9 300 200 49.8 49.8 49.8 48.5 100 100 47.1 47.1 48.5 52.5 200 100 43.1 47.1 45.8 47.1 46.8 300 100 47.1 45.8 43.1 47.1 Locations of the samples Direction Chapter 5 Bed properties 123 Table 5.4 Undrained shear strengths of Bed 2 determined by hand vane tests Distance Distance from the centre from the base North West South East Average of the chamber of the chamber mm mm kPa kPa kPa kPa kPa 100 900 36.3 40.4 35.0 33.7 200 900 37.4 41.7 33.1 34.3 37.5 300 900 39.7 40.4 37.7 39.7 100 800 43.1 41.7 40.4 45.8 200 800 40.4 41.7 43.1 44.4 43.1 300 800 43.1 44.4 43.1 45.8 100 700 48.5 48.5 47.1 56.5 200 700 48.5 45.8 45.8 45.8 47.4 300 700 44.4 47.1 44.4 47.1 100 600 53.8 52.5 51.1 51.1 200 600 51.1 55.2 48.5 51.1 51.1 300 600 49.8 49.8 48.5 51.1 100 500 52.5 51.1 49.8 53.8 200 500 51.1 48.5 52.5 51.1 51.1 300 500 51.1 51.1 51.1 49.8 100 400 53.8 55.2 56.5 56.5 200 400 52.5 51.1 55.2 55.2 53.7 300 400 52.5 49.8 55.2 51.1 100 300 51.1 51.1 52.5 51.1 200 300 52.5 53.8 51.1 51.1 51.3 300 300 49.8 51.1 51.1 48.5 100 200 55.2 53.8 52.5 55.2 200 200 49.8 52.5 52.5 51.1 51.9 300 200 48.5 48.5 52.5 51.1 100 100 56.5 55.2 64.6 56.5 200 100 48.5 51.1 49.8 51.1 52.2 300 100 45.8 49.8 44.4 52.5 Direction Locations of the samples Chapter 5 Bed properties 124 Table 5.5 Undrained shear strengths of Bed 3 determined by hand vane tests Distance Distance from the centre from the top North West South East of the chamber of the chamber Average mm mm kPa kPa kPa kPa kPa 100 100 39.0 40.4 43.1 44.4 200 100 41.7 40.4 41.7 41.7 42.7 300 100 45.8 41.7 45.8 47.1 100 200 41.7 36.3 40.4 40.4 200 200 41.7 40.4 40.4 37.7 41.2 300 200 41.7 43.1 48.5 41.7 100 300 45.8 40.4 40.4 40.4 200 300 41.7 40.4 40.4 39.0 41.7 300 300 41.7 43.1 44.4 43.1 100 400 43.1 43.1 40.4 39.0 200 400 41.7 40.4 40.4 40.4 41.7 300 400 43.1 43.1 43.1 43.1 100 500 41.7 43.1 40.4 40.4 200 500 37.7 45.8 40.4 39.0 42.0 300 500 41.7 45.8 43.1 44.4 100 600 45.8 37.7 41.7 43.1 200 600 40.4 44.4 40.4 40.4 42.2 300 600 44.4 43.1 40.4 44.4 100 700 43.1 44.4 43.1 44.4 200 700 43.1 51.1 43.1 47.1 44.2 300 700 41.7 43.1 43.1 43.1 100 800 47.1 48.5 51.1 49.8 200 800 48.5 44.4 48.5 45.8 47.9 300 800 47.1 47.1 48.5 48.5 100 900 63.3 64.6 66.0 56.5 200 900 48.5 51.1 51.1 56.5 55.2 300 900 48.5 48.5 51.1 56.5 Direction Locations of the samples Chapter 5 Bed properties 125 Table 5.6 Undrained shear strengths of Bed 4 determined by hand vane tests. (Test adjacent to the pile shaft, i.e. 35mm, were horizontal vane tests) Distance Distance from the centre from the top North West South East Mean of the chamber of the chamber value mm mm kPa kPa kPa kPa kPa 100 100 41.7 41.7 39.0 40.4 200 100 40.4 43.1 40.4 40.4 42.0 300 100 45.8 47.1 43.1 40.4 100 200 36.3 35.0 44.4 40.4 200 200 37.7 39.0 40.4 36.3 40.2 300 200 43.1 44.4 40.4 44.4 100 300 52.5 47.1 45.8 53.8 200 300 48.5 49.8 40.4 44.4 47.8 300 300 48.5 53.8 43.1 45.8 100 400 56.5 53.8 51.1 51.1 200 400 51.1 49.8 51.1 53.8 52.4 300 400 56.5 53.8 45.8 53.8 100 500 59.2 53.8 55.2 55.2 200 500 53.8 56.5 53.8 55.2 55.6 300 500 53.8 56.5 59.2 55.2 100 600 56.5 56.5 61.9 56.5 200 600 53.8 57.9 56.5 56.5 57.3 300 600 56.5 60.6 57.9 56.5 100 700 56.5 63.3 60.6 60.6 200 700 56.5 53.8 53.8 55.2 56.6 300 700 56.5 53.8 53.8 55.2 35 (pile shaft) 700 100 800 59.2 60.6 56.5 57.9 200 800 59.2 64.6 61.9 59.2 58.8 300 800 53.8 59.2 59.2 53.8 35 (pile shaft) 800 100 900 56.5 59.2 63.3 56.5 200 900 53.8 56.5 56.5 53.8 57.3 300 900 56.5 56.5 60.6 57.9 35 (pile shaft) 900 96.9 Direction Locations of the samples 107.7 99.6 Chapter 5 Bed properties 126 Table 5.7 Undrained shear strengths of Bed 5 determined by hand vane tests. (Test adjacent to the pile shaft, i.e. 35mm, were horizontal vane tests) Distance Distance from the centre from the top North West South East Mean of the chamber of the chamber value mm mm kPa kPa kPa kPa kPa 100 100 29.6 26.9 26.9 26.9 200 100 29.6 26.9 24.2 26.9 28.2 300 100 31.0 31.0 28.3 29.6 100 200 33.7 35.0 32.3 33.7 200 200 32.3 32.3 29.6 32.3 33.1 300 200 35.0 35.0 33.7 32.3 100 300 37.7 36.3 37.7 37.7 200 300 37.7 37.7 35.0 37.7 37.1 300 300 36.3 37.7 36.3 37.7 35 300 100 400 41.7 39.0 37.7 39.0 200 400 40.4 39.0 37.7 43.1 39.7 300 400 40.4 40.4 37.7 40.4 35 400 100 500 43.1 43.1 39.0 43.1 200 500 43.1 39.0 40.4 43.1 41.8 300 500 43.1 40.4 40.4 44.4 35 (pile shaft) 500 100 600 52.5 51.1 51.1 55.2 200 600 52.5 56.5 52.5 55.2 53.6 300 600 53.8 53.8 52.5 56.5 35 (pile shaft) 600 100 700 56.5 59.2 59.2 60.6 200 700 56.5 53.8 59.2 52.5 55.9 300 700 53.8 51.1 55.2 52.5 35 (pile shaft) 700 100 800 61.9 68.6 57.9 68.6 200 800 52.5 51.1 52.5 53.8 56.3 300 800 51.1 51.1 52.5 53.8 35 (pile shaft) 800 100 900 56.5 55.2 53.8 57.9 200 900 49.8 48.5 45.8 45.8 50.0 300 900 48.5 45.8 47.1 45.8 86.1 148.1 94.2 91.5 60.6 80.8 Direction Locations of the samples Chapter 5 Bed properties 127 Table 5.8 Moisture contents of Bed 1 Sample Distance Distance number from the centre from the base of the chamber of the chamber North West South East mm mm % % % % 1 0 900 2 100 900 25.3 3 100 900 25.3 4 100 900 24.9 5 100 900 25.4 6 200 900 24.8 7 200 900 25.4 8 200 900 25.1 9 200 900 24.9 10 200 900 24.8 11 300 900 25.1 12 300 900 25.0 13 300 900 24.6 14 35 (pile shaft) 700 15 100 700 24.6 16 100 700 24.7 17 100 700 24.7 18 100 700 24.1 19 200 700 24.7 20 200 700 25.6 21 200 700 24.5 22 200 700 24.9 23 300 700 25.6 24 300 700 24.8 25 300 700 24.2 26 35 (pile shaft) 500 27 100 500 24.5 28 100 500 24.1 29 200 500 25.4 30 200 500 23.8 31 200 500 25.2 32 300 500 25.2 33 300 500 24.9 34 300 500 24.9 35 100 300 24.4 36 200 300 24.4 37 300 300 25.2 38 100 Tip 25.1 39 200 Tip 25.6 40 300 Tip 25.1 Moisture content 25.5 24.3 23.6 Directions Chapter 5 Bed properties 128 Table 5.9 Moisture contents of Bed 2 Table 5.10 Moisture contents of Bed 3 Sample Distance Moisture Note number from the bottom content of the sample mm % 1 800 20.2 Sample at the pile shaft 2 800 24.9 3 600 22.6 4 600 24.5 5 400 23.7 6 400 20.3 7 200 25.7 8 200 22.9 Sample Distance Moisture Note number from the bottom content of the sample mm % 1 200 24.9 2 200 25.8 3 200 20.1 Sample at the pile shaft 4 300 24.9 5 300 24.4 Sample at the pile shaft 6 300 25.6 7 400 25.1 8 500 24.0 Sample at the pile shaft 9 500 25.3 10 500 25.0 11 600 25.5 12 600 22.4 Sample at the pile shaft 13 700 26.1 14 700 22.0 Sample at the pile shaft 15 900 25.3 17 900 27.8 18 Pile tip 19.5 Sample at the pile tip Chapter 5 Bed properties 129 Table 5.11 Moisture contents of Bed 4 Sample Distance Moisture Note number from the bottom content of the sample mm % 1 900 21.2 2 900 20.6 3 900 21.2 Sample at the pile shaft 4 700 20.8 5 700 20.6 6 700 17.1 Sample at the pile shaft 7 600 17.4 Sample at 20mm from the pile shaft 8 600 16.9 Sample at the pile shaft 9 600 17.7 Sample at the pile shaft 10 500 21.0 11 500 20.1 12 500 18.9 Sample at 15mm from the pile shaft 13 500 19.3 Sample at the pile shaft 14 500 18.6 Sample at the pile shaft 15 400 18.0 Sample at 25mm from the pile shaft 16 400 17.3 Sample at the pile shaft 17 300 20.3 18 300 17.3 Sample at the pile shaft 19 200 20.0 20 200 20.3 21 200 16.1 Sample at the pile shaft 22 Pile base 16.1 Sample at the pile tip 24 20 mm from pile tip 16.0 Distances to 25 40 mm from pile tip 18.8 the pile tip 26 60 mm from pile tip 19.3 in vertical 27 100 mm from pile tip 20.5 direction Chapter 5 Bed properties 130 Table 5.12 Moisture contents of Bed 5 Table 5.13 Shear strengths from undrained triaxial tests Sample Distance Moisture Note number from the bottom content of the sample mm % 1 900 20.4 2 900 20.6 3 900 20.7 4 800 17.5 Sample at the pile shaft 5 700 20.5 6 700 20.2 7 700 20.3 8 700 18.9 Sample at the pile shaft 9 500 20.2 10 500 20.5 11 500 20.1 12 500 19.6 Sample at 35mm from the pile shaft 13 300 19.8 14 300 19.1 Sample at 85mm from the pile shaft 15 300 17.6 Sample at 35mm from the pile shaft 16 300 16.5 Sample at the pile shaft 17 Pile base 15.1 Sample at the pile tip 19 30 mm from pile tip 14.9 Distances to 20 50 mm from pile tip 16.1 the pile tip 21 100 mm from pile tip 18.1 in vertical 22 120 mm from pile tip 19.1 direction Sample Confining Shear Mean Bed number pressure strength values kPa kPa kPa 1 100 51.5 2 250 49.0 3 300 52.1 50.6 1 4 400 49.6 1 200 49.9 2 250 51.0 3 300 51.7 51.3 2 4 400 52.7 1 200 55.1 2 300 64.9 62.8 3 3 400 68.5 1 250 49.6 2 300 50.1 49.5 4 3 400 48.9 1 150 52.6 2 200 55.2 3 300 52.0 53.1 5 4 350 52.5 Chapter 5 Bed properties 131 Figure 5.1 Bed settlements during 1-D consolidation Figure 5.2 Pore water pressure distribution during 280 kPa 1-D consolidation of Bed 1 0 100 200 300 400 500 600 700 800 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Pore water pressure (kPa) H ei gh t ( m m ) t = 0 hour t = 12 hours t = 84 hours t = 120 hours t = 156 hours t = 192 hours t = 228 hours t = 264 hours t = 300 hours t = 356 hours 0 50 100 150 200 250 300 350 400 450 500 0 50 100 150 200 250 300 350 400 450 500 550 600 Time (Hours) Se ttl em en t ( m m ) Bed 1 Bed 2 Bed 3 Bed 4 Bed 5 Chapter 5 Bed properties 132 Figure 5.3 Pore water pressure distribution during 280 kPa 1-D consolidation of Bed 2 Figure 5.4 Pore water pressure distribution during 280 kPa 1-D consolidation of Bed 3 0 100 200 300 400 500 600 700 800 900 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Pore water pressure (kPa) H ei gh t ( m m ) t = 0 hour t = 84 hours t = 156 hours t = 228 hours t = 336 hours t = 408 hours t = 456 hours t = 504 hours t = 552 hours t = 570 hours 0 100 200 300 400 500 600 700 800 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Pore water pressure (kPa) H ei gh t ( m m ) t = 0 hour t = 36 hours t = 60 hours t = 120 hours t = 156 hours t = 192 hours t = 228 hours t = 255 hours t = 293 hours t = 336 hours t = 360 hours t = 408 hours Chapter 5 Bed properties 133 Figure 5.5 Pore water pressure distribution during 280 kPa 1-D consolidation of Bed 4 Figure 5.6 Pore water pressure distribution during 240 kPa 1-D consolidation of Bed 5 0 100 200 300 400 500 600 700 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Pore water pressure (kPa) H ei gh t ( m m ) t = 0 hour t = 12 hours t = 36 hours t = 60 hours t = 84 hours t = 156 hours t = 192 hours t = 264 hours t = 300 hours t = 338 0 100 200 300 400 500 600 700 0 20 40 60 80 100 120 140 160 180 200 220 240 260 Pore water pressure (kPa) H ei gh t ( m m ) t = 0 hour t = 12 hours t = 36 hours t = 84 hours t = 156 hours t = 210 hours t = 264 hours t = 295 hours t = 336 hours t = 360 hours t = 435 hours Chapter 5 Bed properties 134 Figure 5.7 The final transducer locations of Bed 1 (All dimensions in mm) (PW – pore water pressure transducer, AC – Accelerometer) (The number next to the transducer is height above the base) Figure 5.8 The final transducer locations of Bed 2 (All dimensions in mm) (PW – pore water pressure transducer, AC – Accelerometer) (The number next to the transducer is height above the base) W 185350 295 240 130 75 13075 185 240 295 350 E Kulite Kulite Final boundary final level 15 0 70 12 0 initial level 720 PW 720 PW of sample 790 1,0 60 470 PW S295N 185 75 130 240 350 1,0 60 790 of sample Final boundary Kulite 70 14 0 level initial druck final level 15 0 230 PW 475 PW in pile AC17 485 PW mo ve me nt ra ng eC1C2 C4 C5 C7 C6 PW C8 615 PW 720 C3 AC 455 C18 AC 485 C18 73 188 100 165 325 60 180 339 Radial distance from centre the base Height from Height from the base from centre Radial distance W 185350 295 240 130 75 13075 185 240 295 350 E druck druck Final boundary final level 14 0 70 12 0 initial level 450 Ac Ac 480 200 PW of sample 790 1,0 60 500 PW S295N 185 75 130 240 350 1,0 60 790 of sample Final boundary druck 70 12 0 level initial druck final level 14 0 730 PW 350 PW 390 PW 410 PW in pile Ac 720 PWm ov em en t ra n g e C17 C18 C5 C1 C2 C3 C4 C7 C6 PW C8 700 185 145 110 65 105 175 200 Radial distance from centre above the base Height above the base Height from centre Radial distance Chapter 5 Bed properties 135 Figure 5.9 The final transducer locations of Bed 3 (All dimensions in mm) (PW – pore water pressure transducer, AC – Accelerometer) (The number next to the transducer is height above the base) 790 295 790 170 1,0 60 NW c22 170 17 0 120 75 75 120 level initial 1 2 0 level final druckc21 Ac 100 150 Ac PW 150 c2 SE Ac in pile 70 druck of sample Final boundary c25 790 450 185 430 Ac 1,0 60 350W 295 240 Ac Ac 450c17 c24 of sample 450 1 2 0 final level 75 1 7 0 75 130 Ac initial level in pile druck Ac c4 350 PW c5 PW 390 350240185 295 E 410 PW c7 500 druck c23 70 c1 PW 1,0 60 N Final boundary of sample 70 12 0 17 0 185 75 final level druck in pile Ac level initial 130 Ac 240 350 c18 150 mo ve me n t ra n g e 760 740 PW PW druck c3 c6 c8 720 PW S Final boundary 300 245 130 45 165130 225 Height above the base Radial distance from centre Radial distance from centre the base Height above the base Height above distance from centre Radial Chapter 5 Bed properties 136 Figure 5.10 The final transducer locations of Bed 4 (All dimensions in mm) (PW – pore water pressure transducer, AC – Accelerometer) (The number next to the transducer is height above the base) NW 170 120 12075 170 SE druck druck Final boundary final level 17 0 70 18 5 initial level of sample 790 1,0 60 in pile Ac 1,0 60 17 0 EW 240240350 295 185 130 7575 130 185 295 350 ac 255 495 pw 380 pw 384 460 Ac 18 5 druck level final PW 85 in pile level initial Ac 410 ac PW druck 70 790 of sample Final boundary 17 0 1,0 60 35024013075185N 295 S level final druck initial level 70 druck640 ac 18 5 mo ve me nt r a ng e PW 638 790 Final boundary of sample Ac 460 442 Ac 710 PW Ac in pile C1 C7 c6 C8 C4 c3 75 C21 C17 C22 C23 C18 C24 65 110 165 115 165 260 125 155 250 315 204 Height above the base Radial distance from centre Height above the base distance from Radial centre distance from Radial centre Height above the base Chapter 5 Bed properties 137 Figure 5.11 The final transducer locations of Bed 5 (All dimensions in mm) (PW – pore water pressure transducer, AC – Accelerometer) (The number next to the transducer is height above the base) 220 230 240 250 260 270 280 290 300 0 50 100 150 200 250 300 350 400 Time (ms) Pr es su re (k Pa ) Vertical consolidation pressure 1 (Before modifying the connection between the loading frame and the top chamber plate) Vertical consolidation pressure 2 (After modifying the connection between the loading frame and the top chamber plate) Lateral consolidation pressure 2 (After modifying the connection between the loading frame and the top chamber plate) Lateral consolidation pressure 1 (Before modifying the connection between the loading frame and the top chamber plate) Figure 5.12 Fluctuation of top and side cell pressures during a rapid pile load test 1,0 60 17 5 EW 240240350 295 185 130 7575 130 185 295 350 ac 430440 pw 325 300 Ac 18 5 druck level final PW 120 in pile level initial Ac PW druck 70 790 of sample Final boundary 17 5 1,0 60 35024013075185N 295 S level final druck initial level 70 druck 668 ac 18 5 mo v e me nt ra ng e 790 Final boundary of sample Ac 550 480 Ac Ac in pile C1 C7 C2 C18 C17 C24 C21 C22 620 pw C4 185 80 70 200 110 210 285 Height above the base Radial distance from centre Height above the base from centre Radial distance Chapter 5 Bed properties 138 -30 -20 -10 0 10 20 30 40 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 Time (ms) Po re p re ss ur e (k Pa ) 0 50 100 150 200 250 300 350 400 450 To p ce ll pr es su re (k Pa ) Top cell pressure Pile tip pore pressure Pile skin pore pressure Channel 1 pore pressure Channel 7 pore pressure Channel 6 pore pressure Figure 5.13 Changes of pore pressures in the clay bed due to the drop of the top cell pressure 0 5 10 15 20 25 30 35 40 2485 2505 2525 2545 2565 2585 2605 2625 2645 2665 2685 Time (ms) Po re p re ss ur e (k Pa ) 0 50 100 150 200 250 300 350 400 450 To p ce ll pr es su re (k Pa ) Top cell pressure Pile tip pore pressure Pile skin pore pressure Channel 1 pore pressure Channel 7 pore pressure Channel 6 pore pressure Figure 5.14 Changes of pore pressures in the clay bed due to the drop of the top cell pressure over a period of 200ms