【摘要】：堆積碎石土是土石混合體的一種,由強(qiáng)度較高的碎石和強(qiáng)度較低的土體,經(jīng)復(fù)雜成因形成的土與塊石的二重介質(zhì)混合體。由堆積碎石土組成的坡體和滑坡廣泛存在于我國(guó)各地(尤其是南方地區(qū)),容易引起工程滑坡或坍塌,帶來(lái)巨大的經(jīng)濟(jì)損失和人員傷亡。國(guó)內(nèi)外學(xué)者對(duì)土石混合體力學(xué)特性和變形機(jī)制的研究越來(lái)越多,早期以室內(nèi)試驗(yàn)或室外原位試驗(yàn)研究手段為主。隨著離散元軟件的出現(xiàn),為土石混合體不連續(xù)介質(zhì)的數(shù)值模擬提供了可靠的平臺(tái),并且數(shù)值模擬試驗(yàn)花費(fèi)相對(duì)較低,精確性又能夠得到保證,越來(lái)越受到研究學(xué)者的青睞。但是,在運(yùn)用離散元軟件進(jìn)行數(shù)值模擬之前必須找到反映材料宏觀特性的細(xì)觀參數(shù)。由于細(xì)觀參數(shù)與材料自身的宏觀力學(xué)參數(shù)間存在諸多難以控制因素,并且這些因素之間非線性極為顯著,獲得兩者之間關(guān)系極其不容易,則細(xì)觀參數(shù)標(biāo)定一般采用試湊法獲得,并且此過(guò)程需耗費(fèi)大量的時(shí)間和精力。為此,本文以昭山地區(qū)的堆積碎石土室內(nèi)試驗(yàn)為基礎(chǔ),運(yùn)用PFC3D離散元軟件生成含有不同形狀碎石塊的1:1堆積碎石土數(shù)值模型,通過(guò)標(biāo)定得到相應(yīng)地細(xì)觀參數(shù)(相對(duì)誤差控制在10%以內(nèi))。改變細(xì)觀參數(shù),定量探討其和宏觀力學(xué)參數(shù)(粘聚力和內(nèi)摩擦角)之間的關(guān)系,得到細(xì)觀參數(shù)與宏觀力學(xué)參數(shù)間的的細(xì)-宏觀參數(shù)關(guān)系式,并對(duì)其可靠性進(jìn)行了驗(yàn)證。主要結(jié)論如下:(1)粘聚力與接觸粘結(jié)力、顆粒摩擦系數(shù)關(guān)系為線性正相關(guān);同時(shí)受粘結(jié)力比值M=/c c??的影響,當(dāng)M1時(shí),粘聚力隨著M的增加而線性增加;M≥4時(shí),粘聚力基本保持不變;(2)內(nèi)摩擦角與顆粒摩擦系數(shù)呈對(duì)數(shù)關(guān)系,與接觸粘結(jié)力呈拋物線關(guān)系;(3)得到了細(xì)觀參數(shù)-宏觀力學(xué)參數(shù)的聯(lián)合關(guān)系式,通過(guò)了可靠性驗(yàn)證。細(xì)觀參數(shù)-宏觀力學(xué)參數(shù)關(guān)系式是在含水率為7%的室內(nèi)試驗(yàn)結(jié)果基礎(chǔ)上得出的,將關(guān)系式運(yùn)用到含水率為9%、11%和13%的室內(nèi)試驗(yàn)結(jié)果進(jìn)行標(biāo)定驗(yàn)證:依據(jù)含水率為9%和11%、13%室內(nèi)試驗(yàn)得到的c、?值,運(yùn)用細(xì)-宏觀參數(shù)關(guān)系式計(jì)算得到細(xì)觀參數(shù),經(jīng)驗(yàn)證其數(shù)值-室內(nèi)試驗(yàn)結(jié)果相對(duì)誤差在10%以內(nèi),說(shuō)明通過(guò)細(xì)-宏觀力學(xué)關(guān)系式得到的細(xì)觀參數(shù)符合精度要求,關(guān)系式可靠。為后續(xù)土石混合體數(shù)值試驗(yàn)研究進(jìn)行細(xì)觀參數(shù)標(biāo)定工作提供了參考依據(jù)。
[Abstract]:The aggregate gravel soil is a kind of mixed soil and rock, which is composed of high strength gravel and low strength soil, and is formed by complex genesis of mixed soil and rock duplex medium. The slope body and landslide composed of accumulated gravel soil are widely found in all parts of our country (especially in southern China), which can easily cause engineering landslide or collapse, and bring huge economic losses and casualties. There are more and more researches on the mechanical properties and deformation mechanism of soil-rock mixture at home and abroad, and the early research methods are indoor test or outdoor in-situ test. With the emergence of discrete element software, it provides a reliable platform for the numerical simulation of soil and rock mixed discontinuous medium, and the cost of numerical simulation experiment is relatively low, and the accuracy can be guaranteed, which is more and more popular among researchers. However, the meso-parameters reflecting the macroscopic properties of materials must be found before the numerical simulation is carried out by using discrete element software. Because there are many uncontrollable factors between the meso-parameters and the macroscopic mechanical parameters of the material itself, and the nonlinearity between these factors is very significant, it is not easy to obtain the relationship between them, so the calibration of the meso-parameters is usually obtained by means of trial and error. And the process takes a lot of time and effort. In this paper, based on the laboratory test of packed gravel soil in Zhaoshan area, the numerical model of 1:1 gravel soil with different shapes is generated by using PFC3D discrete element software. The corresponding mesoscopic parameters are obtained by calibration (the relative error is controlled within 10%). The relationship between meso-parameters and macroscopic mechanical parameters (cohesion and angle of internal friction) is discussed quantitatively. The relationship between meso-parameters and macro-mechanical parameters is obtained, and its reliability is verified. The main conclusions are as follows: (1) the relationship between cohesive force and contact adhesion, particle friction coefficient is linear positive correlation, and the adhesion ratio M / c? When M1, the cohesive force increases linearly with the increase of M, when M 鈮，

本文編號(hào)：2320443