本文選題：FLAC3D4.0　切入點(diǎn)：基坑降水　出處：《太原理工大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著城市密度的逐步增大,建筑物之間的間距已經(jīng)縮小至極限,這就提高了對(duì)基坑支護(hù)的有關(guān)要求。對(duì)基坑周邊建筑物的沉降及控制基坑的水平位移也相應(yīng)的提出了挑戰(zhàn)。另外,基坑降水可能引起的土體沉降及支護(hù)結(jié)構(gòu)的變形隨著不同土層的滲透系數(shù)的不同自然也有差異。所以對(duì)于基坑支護(hù)及降水所引起的沉降的影響因素很多,甚至于這些因素之間的相互作用,都可能在對(duì)周邊沉降控制比較嚴(yán)格的基坑或者開(kāi)挖比較深的基坑的沉降控制中起著至關(guān)重要的作用,如何能夠在支護(hù)及降水中將這些因素考慮的比較全面及合理,是一個(gè)亟待研究和解決的問(wèn)題。 為了研究降水過(guò)程中各種參數(shù)對(duì)周邊土體的沉降及水平位移的影響,本文對(duì)基坑降水,土體的變形以及對(duì)支護(hù)結(jié)構(gòu)的變形的理論研究進(jìn)行了詳細(xì)闡述,并采用FLAC3D4.0建模,同時(shí)采用其含有的滲流模塊的模式進(jìn)行計(jì)算,對(duì)降水及開(kāi)挖引起的周邊土體的沉降及支護(hù)結(jié)構(gòu)的變形進(jìn)行了研究與分析,得出了有關(guān)參數(shù)的影響作用的大小。 (1)本文通過(guò)改變基坑支護(hù)結(jié)構(gòu)地下連續(xù)墻的模量,改變基坑支護(hù)結(jié)構(gòu)內(nèi)外的水頭差及基坑支護(hù)結(jié)構(gòu)中的支撐的位置,分別分析了降水及開(kāi)挖過(guò)程中各個(gè)參數(shù)對(duì)連續(xù)墻的彎矩,周邊土體的豎向及側(cè)向變形,支撐的軸力的影響。 (2)本文還對(duì)FLAC3D中的摩爾庫(kù)侖模型及Cysoil模型的計(jì)算結(jié)果進(jìn)行了對(duì)比,得出兩種模型的計(jì)算結(jié)果的差異及應(yīng)用效果。 根據(jù)上述的分析得出結(jié)論： (1)M-C模型與C-Y模型相比,彎矩和撐力相差不大,在10%～25%左右,變形值相差較大,沉降C-Y模型的值大,水平位移M-C模型的值大,回彈M-C模型的值大。 (2)當(dāng)連續(xù)墻模量改變時(shí),墻的彎矩隨模量增大而增大,沉降和水平位移隨模量的增大而減小,總撐力幾乎不變。 (3)隨著坑外水位的降低,連續(xù)墻的彎矩和支撐軸力都會(huì)大幅度下降,水平位移和地表沉降也都大幅下降。 (4)隨著土體的模量的增加,墻體彎矩和變形都相應(yīng)減小,土體模量增大3倍,彎矩下降15%,沉降減小30%,水平位移減小25%,支撐軸力變化不大。 (5)改變支撐位置可以優(yōu)化連續(xù)墻和支撐的軸力,增加一道支撐可以顯著降低連續(xù)墻的彎矩和基坑的變形。 (6)坑外動(dòng)水壓力小于降水壓力,坑內(nèi)的動(dòng)水壓力大于降水壓力,坑內(nèi)動(dòng)水壓力會(huì)減小土體的有效應(yīng)力,增加坑底隆起風(fēng)險(xiǎn),抗?jié)B流和抗隆起是相互關(guān)聯(lián)的。
[Abstract]:As the density of cities increases, the spacing between buildings has narrowed to the limit. This raises the requirements for foundation pit support. It also challenges the settlement of buildings around the foundation pit and the control of the horizontal displacement of the foundation pit. In addition, The settlement of soil and the deformation of supporting structure caused by dewatering of foundation pit are different naturally with the different permeability coefficient of different soil layers, so there are many factors that affect the settlement caused by foundation pit support and dewatering. Even the interaction of these factors may play an important role in the settlement control of the foundation pit with strict control of the peripheral settlement or the settlement control of the deeper foundation pit. How to consider these factors comprehensively and reasonably in support and precipitation is an urgent problem to be studied and solved. In order to study the influence of various parameters on the settlement and horizontal displacement of surrounding soil in the process of dewatering, the theoretical study of foundation pit dewatering, deformation of soil and deformation of supporting structure is described in detail in this paper, and the FLAC3D4.0 model is used. At the same time, by using the model of seepage module, the settlement of surrounding soil and the deformation of supporting structure caused by precipitation and excavation are studied and analyzed, and the effect of relevant parameters is obtained. 1) by changing the modulus of underground continuous wall of foundation pit support structure, changing the water head difference inside and outside of foundation pit support structure and the position of support in foundation pit supporting structure, the paper analyzes the dewatering and the bending moment of each parameter to continuous wall during excavation, respectively. The vertical and lateral deformation of the surrounding soil and the influence of the axial force of the bracing. 2) in this paper, we also compare the calculation results of the Moore Coulomb model and the Cysoil model in FLAC3D, and get the difference between the results of the two models and their application results. On the basis of the above analysis, it is concluded that:. Compared with the C-Y model, the bending moment and bracing force of the M-C model are not different from those of the C-Y model. The deformation value of the model is about 25%, the value of the settlement C-Y model is large, the value of the horizontal displacement M-C model is large, and the value of the springback M-C model is larger than that of the horizontal displacement M-C model. 2) when the modulus of the continuous wall is changed, the bending moment of the wall increases with the increase of the modulus, the settlement and horizontal displacement decrease with the increase of the modulus, and the total supporting force is almost unchanged. 3) with the decrease of the water level outside the pit, the bending moment and the supporting axial force of the continuous wall will be greatly reduced, and the horizontal displacement and the surface subsidence will also be reduced significantly. 4) with the increase of soil modulus, the bending moment and deformation of the wall decrease accordingly, the modulus of the soil increases by 3 times, the bending moment decreases by 15 times, the settlement decreases by 30%, the horizontal displacement decreases by 25%, and the axial force of the support does not change much. 5) the axial force of continuous wall and bracing can be optimized by changing the position of bracing, and the bending moment of continuous wall and deformation of foundation pit can be significantly reduced by adding one bracing. 6) the dynamic water pressure outside the pit is less than the precipitation pressure, and the dynamic water pressure in the pit is greater than the precipitation pressure. The dynamic water pressure in the pit will reduce the effective stress of soil and increase the risk of uplift at the bottom of the pit. The anti-seepage flow and the anti-uplift are interrelated.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU46

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