本研究為利用數值分析軟體UDEC模擬節理岩盤之承載能力，針對一組規則節理之不同岩性岩盤承受建物荷重，在節理勁度與傾角變化之組合情況下，分析基礎下方岩盤之主應力傳播、基礎底面沉陷與地中垂直變位分佈。首先針對節理傾角固定為45˚情況下，探討四種節理勁度比變化與兩種岩性變化組合下之最大主應力部分等壓線分佈之定性與定量特性，同時在位移方面也就基礎底面沉陷槽與地中垂直變位等位移線進行分佈歸納。接著由傾角為45˚，擴充至六種節理傾角(0˚、30˚、45˚、60˚、75˚、90˚)，就節理勁度比變化對最大主應力、基礎底面沉陷、地中垂直變位分佈進行綜合對比。
研究發現當傾角=45˚時，最大主應力傳遞等壓線呈兩股分岐，於kn/ks≧50/1兩股分岐分佈相當。當傾角>45˚時，順著節理方向之分歧線明顯大於垂直節理方向之分歧線；當傾角<45˚時，垂直節理方向之分歧線明顯大於順著節理方向之分歧線，惟兩股分歧之相對大小受kn/ks比值影響甚大，此外傾角變化於kn/ks=1/1時，對基礎底面之最大沉陷量由小到大依序為傾角為90°<75°<45°<60°<30°<0°。

The paper adopts UDEC, a discrete element program, to study the effect of the joint stiffness with various dip angles on the deformation and stress distribution in a rock mass induced by an upper structure. Moreover, the building settlement is also of interest. A simple case with a given dip angle is firstly considered. Then, other conditions with different joint stiffness and dip angle are examined.
In the first part, two condition of hard and soft rock are used. Four sets of the joint stiffness value with a given dip angle of 45˚ are employed. The focus is then to quantify the variation of maximum induced stress values. Accordingly, the deformation and stress distribution in the rock mass and the building settlement are studied of various dip angle (0˚, 30˚,
45˚,60˚, 75˚, 90˚) and joint stiffness ratio kn/ks(1/1,5/1,10/1,50/1) with constant shear stiffness 100MPa.
The analytical results exhibited that at 45˚ dip angle the stress distribution included the parallel-type and orthogonal-type. Further, when kn/ks≧50/1, the depths of the two distribution shape were similar. Moreover, The kn/ks value indicated its significant effect on the shape of the stress contour. At various dip angles, it is observed that the parallel-type or orthogonal-type dominated the stress contours when the angle was large or smaller than 45˚, respectively. In addition to the stress variation, the building settlement was obtained to be largest at 0˚ dip angle and to be smallest at 90˚ dip angle. The increase of the building settlement can be arranged according to the variation of the deep angle as 90˚<75˚<45˚<60˚<30˚<0˚.

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