摘要
岩土边坡稳定问题一直是岩土工程界广泛关注的问题。注浆微型钢管组合桩作为一种新型抗滑结构,以其施工方便、适应能力强等优点在边坡加固和滑坡治理尤其是一些应急、抢修工程中都得到了广泛应用,但目前对于微型组合桩的抗滑作用机理尚缺乏系统全面的认识。
论文主要对注浆微型钢管组合桩在土质边坡中的抗滑工作性状开展模型试验研究。考虑不同的微型桩组合截面形式,对单排微型桩、桩排距分别为2D(D为微型桩的直径)、4D、6D和8D的矩形截面微型组合桩以及桩间距分别为2.5D、4D和6D的圆形截面微型组合桩进行了室内模型试验。根据模型试验结果,对矩形截面和圆形截面组合形式下注浆微型钢管组合桩的荷载分布特征、桩的内力变形特征及其破坏模式进行了分析,给出了不同工况下微型组合桩的工作性状。试验研究结果表明：微型组合桩从开始承担水平推力到破坏可分为三个阶段,分别为弹性变形阶段、塑性变形阶段和破坏阶段,且不同的阶段,各单桩的受力存在一定的差异；微型组合桩中各单桩的破坏模式为双塑性铰破坏。组合桩内的各桩排间距越小,各桩后塑性区土体发生应力重叠的几率越大,从而可能导致组合桩整体抗滑性能的下降；而组合桩内各桩排间距越大,则组合桩的整体协调性能也就越差,同样可以导致组合桩整体抗滑性能的降低,因此,合理的桩间距应该使群桩不利效应相对较低而整体协调性能相对较高,从而能够使微型组合桩发挥其最大的承载性能。本次模型试验中,排距为6D的矩形截面微型组合桩和桩距为6D的圆形截面微型组合桩的加固效果最佳,建议在实际工程中可优先考虑采用桩排距为6D的矩形截面或桩间距为6D的圆形截面微型组合桩。
Geotechnical slope stabilization problem has been becoming one of most important problems in geotechnical engineering field at all times.Grouted micro steel-tube composite pile is a new type of retaining structure.With the advantage of its convenient construction and strong adaptability, the composite piles are widely used in slope stabilization and landslide remediation, especially in emergency repair projects.However, it is lack of systematic and comprehensive understanding on how and why the technique works.
In this article,model tests are done to study the anti-sliding behavior of the grouted micro steel-tube composite piles in earth slope.In consideration of different section shape of composite micropiles, the testing programs are divided into three sets, that is, one row pile model;rectangle cross section composite micropile models with row distances of 2D,4D,6D and 8D (D is pile diameter);and circular cross section composite micropile models with pile spacings of 2.5D,4D and 6D.Based on the test results, the load distribution characteristic, the internal force and deformation behaviors of piles, and the failure modes of rectangle and circular cross section composite micropiles are analyzed. The behavior characteristics of composite micropiles under different operating mode are proposed. The experiment results indicate three behavioral stages of composite micropiles,that is, elastic deformation stage,plastic deformation stage and failure stage.The mobilized force of each pile differs in different stage.The damage form of each pile in composite micropiles can be defined as double plastic hinges failure.When the pile spacing or row distance decreases,the probability of the plastic zone of soil behind the micropiles cross and overlap increases,which may degrade the overall anti-sliding performance of micropiles;on the contrary, when the pile spacing or row distance increaces, the overall coordination performance of micropiles degrades, which also can degrade the overall anti-sliding performance of micropiles.Therefore, reasonable pile spacing should reduce the adverse group effect of micropiles relatively, improve the overall coordination performance of micropiles relatively and can mobilize the greatest lateral bearing capacity. In this testing programs, rectangle cross section composite micropiles with row distance of 6D and circular cross section composite micropiles with pile spacing of 6D have optimum reinforcement effect, so these two geometric arrangements are suggested to be considered as priority in practical projects.
引文
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