Mechanical behavior of soft clay improved with lime cloumn during vertical excavation

研制了一种可在空中模拟开挖过程的离心式挖掘机，并对离心式挖掘机在软粘土开挖过程中的力学行为进行了研究。在这项研究中，进行了三个系列的离心试验。在第一个系列中，不排水强度随深度增加的垂直切口的稳定性的影响进行了研究，在离心模型试验中，准备的模型被带到失败，通过增加离心加速度。在第二个系列中，使用挖掘机对两种类型的软粘土（即正常固结粘土和轻度超固结粘土）进行无支撑开挖和带或不带连接件的支撑墙开挖。土压力板桩墙和变形的墙壁和粘土开挖过程中进行了测量。在第三个系列中。在正常固结粘土中采用无拉结支护墙开挖，主动侧采用石灰桩进行改良 ...更多信息 是用挖掘机进行的。通过对试验结果的分析，得出以下结论：1）无拉筋板桩墙支护的基坑破坏机理，对于强度均匀的粘性土地基和强度递增的粘性土地基是不同的。对于前者，墙在主动侧和被动侧均表现出平移运动，且滑动面均为线性;而对于后者，墙仅在主动侧表现出绕底部倾斜的线性滑动面。3）活动状态下粘土的性质对板桩墙的变形和应变有显著影响; 4）在无拉结板桩活动侧加石灰桩的加固措施，减小了板桩的应变和作用在板桩墙上的主动压力，对提高基坑的稳定性没有明显作用。少

A centrifuge excavator with which the process of excavation can be simulated in-flight was developed and a study on the mechanical behavior of soft clay during excavation using the centrifuge excavator is reported here. In this study three series of centrifuge tests were carried out. In the first series, the effect of undrained strength increase with depth on the stability of vertical cuts was investigated by centrifuge model tests in which prepared models were brought to failure by increasing centrifugal acceleration. In the second series, unsupported excavation and excavation with a supporting wall with or without ties were conducted with the excavator for two types of soft clay, namely normally consolidated and lightly overconsolidated clays. Earth pressures on sheet pile walls and deformations of the walls and clay were measured during excavation. In the third series. excavation with supporting wall without tie for normally consolidated clay improved with lime piles in active side … More were conducted by using the excavator. The effect of improvement and mechanical behavior of improved groud during excavation were investigated.The analyzes of the test results provided the following conclusions.1)The mechanism of failure in excavation with sheet pile walls without ties is different for clay grounds with uniform strength and increasing strength. For the former the wall shows translational movement with well-defined linear slip surface both in the active and passive side, while for the latter the wall tilts around the bottom with linear slip surface only in the active side.2)In excavation with sheet pile walls without ties, the embedment does not contribute to the stability in clay with uniform strength. but stability number increases significantly with depth of embedment in clay with increasing strength.3)The characteristics of clay in the active state have a dominant effect on the deformations and strains of sheet pile walls.4)The improvement with lime piles in the active side of sheet pile without tie reduces strains of sheet pile and active pressures on sheet pile walls, and in effective in increasing the stability of excavation. Less