土质斜坡坡顶沉桩对指定滑动面安全系数影响分析
Effect of pile driving adjacent to soil slopes on safety factor of specific sliding surface
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摘要: 利用边坡稳定性计算方法,基于球孔弹塑性扩张理论,研究了沉桩力、桩端塑性区以及桩体抗滑作用对沉桩过程中滑动面安全系数的影响。通过算例,对沉桩全过程中滑动面安全系数变化进行了研究,并对桩径,边坡角度以及沉桩距边坡顶点距离对沉桩过程中边坡滑动面安全系数变化的影响进行了分析。结果表明:沉桩力及桩端塑性区对滑动面稳定性产生不利影响,使安全系数降低;当桩体穿过滑动面之后,桩体起到抗滑作用,显著提高滑动面安全系数。桩径越大,沉桩前期安全系数下降速度越快,但桩端穿过滑动面后安全系数提升也更加显著;边坡角度越大,沉桩后边坡安全系数越小;沉桩离边坡顶点越远,在沉桩前期由于沉桩力导致的安全系数下降速度越慢,塑性区对安全系数的影响也逐渐减缓,当沉桩远离边坡顶点距离达到一定值后,沉桩将不再对滑动面稳定性产生影响。分析结果对邻近边坡沉桩的设计和施工具有一定的实用价值。Abstract: The effect of pile driving force, plastic zone around the pile tip and anti-sliding action of the pile body on safety factor of sliding surface is investigated by using the stability calculation methods for slopes based on the cavity expansion theory with the consideration of elasto-plasticity of soil. Through a numerical case, change of safety factor in the whole process of the pile driving is analyzed. And the effect of pile diameter, slope angle and distance between pile and slope top on the change of safety factor of slope is discussed. The results show that the pile driving force and the plastic zone at pile top have an adverse effect on slope stability, which leads to a decrease in the safety factor, while the anti-sliding effect of the pile has a positive contribution to the slope stability, especially when the end of pile is below the sliding surface. The safety factor decreases significantly with the increase of the pile diameter, and it significantly increases after the pile end penetrates through the sliding surface. The greater the slope angle, the smaller the safety factor after pile driving. The safety factor drops more slowly with the increase of the distance of the pile away from the slope top, and the effect of the plastic zone on the safety factor also gradually decreases. The pile driving will not affect the stability of the sliding surface when the pile is far from the top of the slope. The results may provide some guiding significance and reference value for the design and construction of static pile driving adjacent to slopes.