【摘要】：以粘性土以及凍土材料為研究對(duì)象，進(jìn)行了粘性土和凍土在沖擊荷載作用下的動(dòng)態(tài)本構(gòu)關(guān)系的研究，開(kāi)展的研究工作和取得的成果如下： 首先，進(jìn)行了粘性土在準(zhǔn)靜態(tài)加載條件下的無(wú)側(cè)限抗壓試驗(yàn)，獲得了粘性土的靜態(tài)力學(xué)參數(shù)，以便與動(dòng)態(tài)加載條件下粘性土的試驗(yàn)進(jìn)行對(duì)比。為了獲得粘性土在沖擊荷載作用下的動(dòng)態(tài)力學(xué)性能參數(shù)，利用SHPB裝置在500~1200s1的應(yīng)變率范圍內(nèi)，對(duì)粘性土進(jìn)行了動(dòng)態(tài)沖擊壓縮試驗(yàn)。研究表明：粘性土表現(xiàn)出顯著的應(yīng)變率敏感性。 然后，針對(duì)粘性土在沖擊荷載作用下的本構(gòu)模型進(jìn)行研究。從材料彈塑性理論著手，建立了一個(gè)粘性土的準(zhǔn)靜態(tài)彈塑性本構(gòu)方程來(lái)描述其力學(xué)性能，并運(yùn)用損傷力學(xué)中的微孔洞損傷，對(duì)其有效彈性模量進(jìn)行計(jì)算。通過(guò)在原有準(zhǔn)靜態(tài)屈服函數(shù)中加入應(yīng)變率效應(yīng)的影響來(lái)得到一個(gè)適用于粘性土的動(dòng)態(tài)本構(gòu)方程。并對(duì)其中的微孔洞損傷進(jìn)行描述并給出損傷演化方程，建立了一個(gè)損傷與塑性相耦合的本構(gòu)方程。最后運(yùn)用土體的有效應(yīng)力原理，加入粘性土中的孔隙水壓力和孔隙氣壓力。 其次，為了獲得凍土材料在沖擊荷載作用下的動(dòng)態(tài)力學(xué)性能參數(shù)，利用SHPB裝置在-3℃、-8℃、-13℃、-17℃、-23℃、-28℃六個(gè)負(fù)溫下，在300~1200的應(yīng)變率范圍內(nèi)，，對(duì)凍土材料進(jìn)行了動(dòng)態(tài)沖擊壓縮試驗(yàn)，得到了凍土材料的應(yīng)力-應(yīng)變曲線。研究表明：凍土材料表現(xiàn)出顯著的溫度敏感性和應(yīng)變率敏感性。 再次，針對(duì)沖擊荷載作用下凍土的動(dòng)態(tài)力學(xué)性能及本構(gòu)模型展開(kāi)研究。采用復(fù)合材料細(xì)觀力學(xué)中的混合律思想，將凍土材料看做是由土顆�；w和冰顆粒夾雜組成的兩相復(fù)合材料，并假設(shè)土顆粒和冰顆粒為各向同性且均勻的，對(duì)軸向加載情況下的凍土的等效彈性模量和等效泊松比進(jìn)行了計(jì)算�；诓牧系膹椝苄岳碚摚孕拚腄rucker-Prager函數(shù)作為屈服函數(shù)，構(gòu)造了一個(gè)考慮應(yīng)變率效應(yīng)的各向同性強(qiáng)化本構(gòu)模型用于描述凍土材料的沖擊特性。接下來(lái)運(yùn)用損傷力學(xué)中的損傷變量來(lái)描述凍土材料中微裂紋和微孔洞對(duì)凍土動(dòng)態(tài)力學(xué)性能的弱化作用，并給出了損傷演化方程。 最后，為了驗(yàn)證第三章和第五章建立的粘性土、凍土在沖擊荷載作用下的動(dòng)態(tài)本構(gòu)模型的有效性，基于第二章、第五章中的粘性土、凍土的SHPB試驗(yàn)，對(duì)其本構(gòu)方程的參數(shù)進(jìn)行確定，并將模型數(shù)值計(jì)算結(jié)果與試驗(yàn)進(jìn)行對(duì)比。
[Abstract]:The dynamic constitutive relations of cohesive soil and frozen soil under impact load are studied. The results are as follows: firstly, The unconfined compressive tests of clayey soil under quasi-static loading were carried out, and the static mechanical parameters of clayey soil were obtained for comparison with those under dynamic loading. In order to obtain the dynamic mechanical properties of cohesive soil under impact loading, the dynamic impact compression test of cohesive soil was carried out in the range of 500~1200s1 strain rate using SHPB device. The results show that clayey soil exhibits remarkable strain rate sensitivity. Then, the constitutive model of cohesive soil under impact load is studied. A quasi-static elastoplastic constitutive equation of cohesive soil is established to describe its mechanical properties based on the elastic-plastic theory of materials. The effective elastic modulus of cohesive soil is calculated by using the micro-void damage in damage mechanics. By adding the effect of strain rate effect into the original quasi static yield function, a dynamic constitutive equation for cohesive soil is obtained. The damage of microvoids is described and the damage evolution equation is given. A constitutive equation of the coupling of damage and plasticity is established. Finally, the pore water pressure and pore gas pressure in cohesive soil are added by the effective stress principle of soil. Secondly, in order to obtain the dynamic mechanical properties of permafrost materials under impact load, the strain rate of 300,1200 was obtained at six negative temperatures of -3 鈩

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