邊坡工程方面畢業論文設計外文翻譯(編輯修改稿)

　

【文章內容簡介】 irm stratum．Gibson and Morgenstern [] published stability coefficients for slopes in normally consolidated clays in which the undrained strength cu(φu =0) varies linearly with depth．In this method the potential failure surface，in section，is again assumed to be a circular arc with centre O and radius r．The soil mass (ABCD) above a trial failure surface (AC) is divided by vertical planes into a series of slices of width b, as shown in base of each slice is assumed to be a straight line．For any slice the inclination of the base to the horizontal isαand the height, measured on the centre1ine,is h. The factor of safety is defined as the ratio of the available shear strength(τf)to the shear strength(τm) which must be mobilized to maintain a condition of limiting equilibrium, . The factor of safety is taken to be the same for each slice，implying that there must be mutual support between slices，. forces must act between the slices．The forces (per unit dimension normal to the section) acting on a slice are： total weight of the slice，W=γb h (γsat where appropriate)． total normal force on the base，N (equal to σl)．In general thisforce has two ponents，the effective normal force N39。(equal toσ39。l ) and the boundary water force U(equal to ul )，where u is the pore water pressure at the centre of the base and l is the length of the base． shear force on the base，T=τml. total normal forces on the sides, E1 and E2. shear forces on the sides，X1 and X2.Any external forces must also be included in the analysis． The problem is statically indeterminate and in order to obtain a solution assumptions must be made regarding the interslice forces E and X：the resulting solution for factor of safety is not exact． Considering moments about O，the sum of the moments of the shear forces T on the failure arc AC must equal the moment of the weight of the soil mass ABCD．For any slice the lever arm of W is rsinα,therefore∑Tr=∑Wr sinαNow, For an analysis in terms of effective stress，Or ()where La is the arc length AC．Equation is exact but approximations are introduced in determining the forces N39。．For a given failure arc the value of F will depend on the way in which the forces N39。 are estimated． In this solution it is assumed that for each slice the resultant of the interslice forces is zero．The solution involves resolving the forces on each slice normal to the base，.N39。=WCOSαulHence the factor of safety in terms of effective stress (Equation ) is given by ()The ponents WCOSαand Wsinαcan be determined graphically for each slice．Alternatively，the value of αcan be measured or calculated．Again，a series of trial failure surfaces must be chosen in order to obtain the minimum factor of safety．This solution underestimates the factor of safety：the error，pared with more accurate methods of analysis，is usually within the range 52%. For an analysis in terms of total stress the parameters Cu andφu are used and the value of u in Equation is zero．If φu=0 ,the factor of safety is given by ()As N’ does not appear in Equation an exact value of F is obtained．In this solution it is assumed that the resultant forces on the sides of theslices are horizontal，.XlX2=0For equilibrium the shear force on the base of any slice is Resolving forces in the vertical direction: ()It is convenient to substitute l=b secαFrom Equation ，af