【摘要】：蒙河大橋在地理位置上處于蒙河之上,蒙河的河床深度在4-8米之間,河床中主要的物質(zhì)成分：中砂,蒙河河床的中砂層下面還包括0.4 m到1.2m厚沉積性可區(qū)分的粉質(zhì)粘土,粘土土層下面大面積遍布著材質(zhì)堅(jiān)硬的石炭紀(jì)石灰?guī)r。需要特別注意的是,中度和強(qiáng)度程度風(fēng)化的石灰?guī)r大致的厚度程度在1 m的水平,風(fēng)化的石灰?guī)r的下面屬于微風(fēng)化程度的石灰?guī)r。由于地質(zhì)運(yùn)動(dòng)階段河水和地下水之間的相互作用,與此同時(shí)發(fā)生了一系列的反應(yīng),發(fā)生了潛蝕反應(yīng),同時(shí)在重力的作用下,逐步出現(xiàn)了溶洞,溶洞迅速發(fā)育變大,且溶洞內(nèi)大多存在填充物質(zhì),多為可塑性粉質(zhì)性粘土,易于和水發(fā)生反應(yīng)。研究主要針對(duì)橋梁建筑過程中的樁基施工部分,通過明確巖溶地區(qū)勘探方法、樁基承載力模擬計(jì)算確定設(shè)計(jì)階段的處理方案,從設(shè)計(jì)初期盡可能的避開溶洞分布密集的區(qū)域。之后針對(duì)本橋進(jìn)行設(shè)計(jì)方案的比選,確定施工預(yù)處理方案及事故處理預(yù)案。在橋梁建設(shè)開始之前,重新對(duì)每根樁位都進(jìn)行詳細(xì)的地理鉆探,形成詳細(xì)的勘探資料。對(duì)于發(fā)現(xiàn)的溶洞探明其內(nèi)部是否存在填充物,并取樣研究。填充物取樣后對(duì)其進(jìn)行土工試驗(yàn),分析巖溶地區(qū)的填充物的物理力學(xué)特征,測(cè)試填充物的容重、測(cè)試填充物的含水量、測(cè)試填充物的孔隙率等,為下一步進(jìn)行溶洞處理提供相關(guān)的參數(shù)依據(jù)。依據(jù)地質(zhì)鉆探提供的相關(guān)詳細(xì)的資料以及各種各樣的填充物實(shí)際的情況,在施工前針對(duì)存在溶洞的樁基制定預(yù)處理方案及專項(xiàng)施工方案。針對(duì)溶洞易出現(xiàn)事故的施工過程制定出詳細(xì)的處理預(yù)案,針對(duì)施工中出現(xiàn)的事故,參照施工經(jīng)驗(yàn)并結(jié)合現(xiàn)場(chǎng)實(shí)際,選擇合適的處理方案,及時(shí)處理了事故,經(jīng)后期樁基質(zhì)量檢測(cè),符合設(shè)計(jì)及規(guī)范的要求。通過上述研究主要得出如下結(jié)論：在臨沂地區(qū)巖溶地質(zhì)普遍發(fā)育較好的區(qū)域,綜合考慮現(xiàn)階段的施工能力、機(jī)械設(shè)備和技術(shù)水平,采用注漿預(yù)處理和回填造壁法相結(jié)合的施工方法是比較適宜的,這種方案增加成本較低,僅在鉆探及出現(xiàn)溶洞的應(yīng)急處理過程中增加部分施工費(fèi),相比其他施工方案,較為經(jīng)濟(jì)實(shí)用,且對(duì)工期影響較小,性價(jià)比較高。
[Abstract]:The Menghe Bridge lies geographically above the Menghe River. The bed depth of the Menghe River is between 4m and 8m. The main material component in the riverbed is medium sand. The middle sand layer of the Menghe River bed also consists of silty clay with thickness of 0.4 m to 1.2 m, which is covered with hard Carboniferous limestone in a large area under the clay soil layer. Special attention should be paid to the fact that moderately and intensively weathered limestone is roughly 1 m thick and below the weathered limestone belongs to slightly weathered limestone. As a result of the interaction between river water and groundwater during the geological movement, at the same time, a series of reactions and latent corrosion took place. At the same time, under the action of gravity, the cave gradually appeared, and the cave developed rapidly. Most of the caves are filled with plastic silty clay, which is easy to react with water. The research mainly aimed at the pile foundation construction part in the bridge building process, through the clear karst area exploration method, the pile foundation bearing capacity simulation calculation determines the design stage treatment plan, from the design initial stage as far as possible avoids the karst cave distribution dense area. After that, the design scheme of this bridge is compared and selected, and the pre-treatment scheme and accident treatment plan are determined. Before the construction of the bridge begins, every pile is re-drilled in detail to form detailed exploration data. Find out if there are fillers in the cave, and sample it. After sampling the fillers, the geotechnical tests are carried out to analyze the physical and mechanical characteristics of the fillers in karst areas, to test the bulk density of the fillers, to test the moisture content of the fillers, and to test the porosity of the fillers, etc. Provide the relevant parameter basis for the next step of the cave treatment. According to the detailed data provided by geological drilling and the actual situation of various fillers, the pre-treatment scheme and special construction plan for pile foundation with karst cave are made before construction. In view of the accident-prone construction process of karst cave, a detailed treatment plan is made. According to the accident in construction, referring to the construction experience and combining with the actual situation on the spot, the appropriate treatment scheme is selected and the accident is dealt with in time. After testing the quality of pile foundation in the later period, it meets the requirements of design and code. The main conclusions are drawn as follows: in the area where karst geology is generally well developed in Linyi area, the construction capacity, mechanical equipment and technical level of the present stage are considered comprehensively. The construction method combining grouting pretreatment with backfill wall building method is more suitable. This scheme increases the cost of construction and only increases part of the construction cost in the process of drilling and emergency treatment of karst cave, compared with other construction schemes. More economical and practical, and less impact on the time limit, the price of performance is relatively high.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U445.551

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本文編號(hào)：2458653