桩−土界面倾角和含水率对抗滑桩的阻滑效应分析

Slip resistance effect of pile-soil interface inclination angle and moisture content on the anti-sliding pile

为研究不同界面倾角及含水率对桩–土界面的阻滑效果,首先基于变倾角组合体三轴不固结不排水试验,比较了不同界面倾角和含水率条件下变倾角组合体破坏模式和抗剪强度的差异性,然后结合室内试验抗剪强度参数,通过数值模拟方法比较不同界面倾角和含水率对桩–土界面的阻滑效果,并基于塑性变形理论确定临界含水率w_(max),最后依托工程案例对抗滑桩截面进行优化。结果表明:界面倾角和含水率是导致变倾角组合体破坏模式和抗剪强度差异的主要原因,当含水率较低时,适当增大倾角能提高组合体试样的抗剪强度;当土体含水率较小时,随着桩侧倾角的增大,桩–土界面阻滑效果呈现先增加后降低趋势,当桩侧土体含水率较高时,桩–土界面倾角越大,桩–土界面阻滑越小;当考虑桩间土拱效应时,适当增加抗滑桩桩背受压区三角形截面,作用在桩侧摩擦拱上的等效集中荷载最大可降低33%左右。相关研究成果对抗滑桩的设计具有借鉴意义。

To study the slip resistance effect of pile-soil interface with different interface inclination angle and moisture content,the variability of damage modes and shear strengths of assemblies with variable inclination angles under the dif-ferent conditions of interface inclination angles and water content were compared based on the triaxial unconsolidated undrained test at first.Then,the slip resistance effects of the pile-soil interface with different interface inclination angles and moisture contents were compared by numerical simulation,with consideration to the shear strength parameter of laboratory test.Meanwhile,the critical moisture content w_(max) was determined based on the plastic deformation theory.Fi-nally,the cross-section of the anti-sliding pile was optimized based on the engineering case.The results show that inter-face inclination angle and moisture content are the main reasons for the difference in damage mode and shear strength of the assemblies with variable inclination angles.Specifically,an appropriate increase in inclination angle at low moisture content could improve the shear strength of the assembly specimens.In the case of low moisture content in the soil,the slip resistance effect of the pile-soil interface shows a trend of increasing first and then decreasing with the increase of inclination angle on the pile side.At the higher moisture content of the soil on the pile side,the larger the inclination angle of pile-soil interface,the smaller the slip resistance effect of pile-soil interface.Appropriately increasing the trian-gular section of the back pressure area of the anti-sliding pile could reduce the equivalent concentrated load acting on the friction arch of the pile side by about 33%at maximum when consideration is given to the soil arching effect between piles.Generally,the research results could be used for reference in the design of anti-sliding piles.