YIN Ji-chao, BAI Xiao-yu, ZHANG Ya-mei, et al. Development and application of a test device for simulating pile driving and static load in undisturbed mudstone[J]. 2023, 44(S1): 698-710.
DOI:
YIN Ji-chao, BAI Xiao-yu, ZHANG Ya-mei, et al. Development and application of a test device for simulating pile driving and static load in undisturbed mudstone[J]. 2023, 44(S1): 698-710.DOI: 10.16285/j.rsm.2022.1469.
Development and application of a test device for simulating pile driving and static load in undisturbed mudstone
针对泥岩地基打入桩贯入困难、承载力不足现象及软岩易扰动难以制备模型地基的特点,通过原状软岩约束单元、锤击贯入单元、导轨支架单元、静载单元4部分的设计与联系,初步研制了基于原状软岩的模拟打桩与静载试验装置,进行标定及验证性试验、应用试验,验证装置的可行性、稳定性,分析打入桩的沉贯与承载特性,明确桩周泥岩力学特征,提出进一步研究展望与工程应用建议。研究表明:(1)验证性试验、应用试验结果与现场试验结果一致,沉贯特性、承载特性与现场试验相同,验证了试验装置的可行性;(2)荷载传递相关因子稳定性好,进一步证实了试验装置的荷载传递稳定可靠;(3)泥岩软硬互层严重,每10 mm贯入度通过锤击数表征的贯入阻力差异性大,低强度软夹层发生的静载破坏呈现出沉降急剧增大的陡降特征;(4)打桩对桩周2d(d为桩径)范围内的泥岩造成不同梯度的损伤,每间隔0.5d,强度损失66.0%、40.5%、17.0%、7.0%,弹性模量损失80.5%、54.5%、26.5%、11.0%;(5)完善取样技术,加强泥岩软硬互层的勘察判定,增强控制贯入度的施工措施,泥岩地基打入桩承载力的理论分析、数值计算及设计施工,应按损伤梯度合理选取原状力学参数折减后的数值。试验装置具有稳定、可靠、可控等优点,可为泥岩地基动力打入桩的相关研究提供支撑。 In response to the difficulties in driving piles into mudstonefoundation
insufficient bearing capacity
and the difficulty in preparing amodel foundation due to the disturbance of soft rock
a simulation pile drivingand static load test device based on undisturbed soft rock was preliminarilydeveloped. The device mainly includes undisturbed soft rock constraint modelbox unit
hammer-driven unit
guide rail support unit and static load unit. Calibrationtests and application tests were carried out to verify the feasibility andstability of the device. The penetration and bearing characteristics of drivenpile were analyzed
the mechanical characteristics of mudstone around pilecaused by pile driving damage were defined
and further research prospect andengineering application suggestions were put forward. The study shows that: 1)The results of tests are consistent with that of field test
and thepenetration characteristics and bearing characteristics are both the same asthose of field test
which verifies the feasibility of the test device. 2) Thestability of the load transfer factor α further proves that the loadtransfer of the test device is stable and reliable. 3) As mudstone has intensivesoft and hard interbedding
as a result
there is a significant difference inpenetration resistance represented by the number of blows per 10 mm ofpenetration
and the static load failure of low strength soft interlayers presentsa precipitously increasing settlement. 4) The mudstone within 2d (d is the pile diameter) around the pile is damaged by pile driving; for every 0.5d interval
the strength loss is 66.0%
40.5%
17.0%
7.0% and the elasticmodulus loss is 80.5%
54.5%
26.5%
11.0%
respectively. 5) The reduced values of the undisturbedmechanical parameters should be selected according to the damagecharacteristics induced by pile driving in the design and bearing capacityevaluation of mudstone. The test device has the advantages of stability
reliability and controllability
which can provide support for related researchon pile driving in mudstone.
Sealing system design and model testing of lining structures for artificial underground gas storage caverns in medium-hard rock strata
Calculation method of sliding surface stress based on segmented sliding surface stress measurement system
Experimental study on vacuum combined with electro-osmosis for reinforcing ultrafine particle dredged soil
Experimental study on drainage performance of reinforced improved soft rock residual soil under rainfall conditions
Model test of deformation and failure mechanism of gravel soil bank slope under rainfall and reservoir water level
Related Author
CAO Xiao-yong
LIU Rui-hui
LI Jian-fei
YE Xin-xin
GENG Jun-yang
TAN Hai-xing
CHEN Huai-lin
YANG Tao
Related Institution
School of Highway, Chang’an University
CCCC First Highway Consultants Co., Ltd.
State Key Laboratory of Intelligent Construction and Maintenance for Geotechnical and Tunnel Engineering under Extreme Environments, Southwest Jiaotong University
China Northwest Research Institute Co., Ltd., of CREC