| Summary: | 碩士 === 中原大學 === 土木工程學系 === 88 === ABSTRACT
KEY WORDS：Deep excavation engineering、Sung-Shang Formation、horizontal subgrade reaction modulus、elasto-plastic、residual stress
Taiwan is a narrow island crowded with great number of people . As result of highly intensive development of enterprises , the tall buildings have been constructed higher and higher and the excavation of the ground becomes deeper and deeper . The subways , mass transit systems and other public engineering projects continue to develop downward penetrating the earth . Following the completion of the railway running underground in the Greater Taipei Metropolitan Area , the successive mass transmit systems as well as the subterrancan railways shall be carried out in the other cities and counties such as Kaohsiung City , Tainan City ,Taichung City and Tao Yuan City etc . It is believed that the underground excavation work shall be hot topic for the civil engineers to discuss in near future .
Along with the increase of the deep excavation projects , the in-cidents causing the damage to surrounding environment happened frequently from time to time during the digging work . Even the houses in its neighborhood cracks in walls or floors in serious manner , the road surface collapses , and other accident endangers the public safety . Consequently , the retaining structure guard against land slide and its interaction with the soil to hold the balance has been studied by experts and scholars for its importance . How to adopt the reasonable analytical modes and appropriate soil’s variables is the one of motives in the present study.
Now the deep digging cases in the country are centered around the Taipei and Kaohsiung cities , Especially in Taipei , the digging work can be almost seen eberywhere with Mass Transit Systems and subways in addition to numerous small projects . The Taipei Stratum is mainly composed of the Sung-shan Formation . The composition of the Sung-shan Formation consists of earth deposited clays and earth deposited fine sands woven alternately . As the clay layer is not easily grasped by people . Therefore , in the pre-sent studies , we select two engineering projects of deep excavation through clay clayer as examples . Based on the result of actual observation , the feedback analysis to explore the horizontal subgrade reaction modulus which are to be applied the deep excavation analysis .
In the present studies , the theory on the analysis of elasto-plastic with the four different value Kh ( 100Su , 200Su , 150Su , 50Su ) with Mode A equal value horizontal subgrade reaction modulus , Mode B linear horizontal subgrade reaction modulus and Mode C non-linear horizontal subgrade reaction modulus are taken to conduct analysis and research . The result of the studies indicates , the Taipei Basin’s Sung-shan 6th and Sung-shan 4th Layers have the Kh values ranging from 100 Su — 150 Su while 100 Su may be taken as initial Kh value in preliminary analysis . Another research discovers that among the three different modes in the analysis of the horizontal subgrade reaction force modulus, the result obtained from the non-linear horizontal subgrade reaction modulus in Mode c is relatively agreeable with the actual value . It is judged that as the clay layer under the excavate surface had incomplete release of pressure , still there is a sign in holding some residual stress .
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