付録 - 沈み込みとせん断のアプローチの概要

浸透力(Bekker):(1)
p=( k c b + k φ ) D n C D ˙ MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiCaiabg2 da9maabmaabaWaaSaaaeaacaWGRbWaaSbaaSqaaiaadogaaeqaaaGc baGaamOyaaaacqGHRaWkcaWGRbWaaSbaaSqaaiabeA8aQbqabaaaki aawIcacaGLPaaacaWGebWaaWbaaSqabeaacaWGUbaaaOGaeyOeI0Ia am4qaiqadseagaGaaaaa@44BF@
ここで:
  • D = リンク面に垂直な方向のクローラ・履帯リンクの沈み込み量
  • p = 圧力
  • b = クローラ・履帯幅
  • C = 単位面積当たりの減衰係数
  • kc, kΦ, n = 経験的に決定された定数
せん断力(Janosi ):(2)
τ=( c+ptanφ )( 1 e j k ) MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqiXdqNaey ypa0ZaaeWaaeaacaWGJbGaey4kaSIaamiCaiGacshacaGGHbGaaiOB aiabeA8aQbGaayjkaiaawMcaamaabmaabaGaaGymaiabgkHiTiaadw gadaahaaWcbeqaaiabgkHiTmaalaaabaGaamOAaaqaaiaadUgaaaaa aaGccaGLOaGaayzkaaaaaa@48C6@
ここで:
  • τ = せん断応力
  • j = せん断変位
  • c = 凝集力
  • Φ=内部摩擦角
  • k = 経験的に決定された定数
Janosiのアプローチによると、せん断変位を増加させるとせん断応力が増加します。最大せん断応力は:(3)
τ max = c + p tan φ MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqiXdq3aaS baaSqaaiGac2gacaGGHbGaaiiEaaqabaGccqGH9aqpcaWGJbGaey4k aSIaamiCaiGacshacaGGHbGaaiOBaiabeA8aQbaa@4319@

しかし、せん断変位のある値以上であれば、せん断応力は減少します。これは、土壌破壊により土壌パラメータ(cとΦ)が変化したためです。 せん断変位が最大せん断応力に影響し、土質パラメータには影響しないという単純なアプローチをとることを推奨します。提案されたアプローチは、修正Janosiアプローチです。

(4)
τ max ={ c+ptanφ j< j max ( c+ptanφ ) e j max j k 1 j max j j u ( c+ptanφ )r j> j u MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqiXdq3aaS baaSqaaiGac2gacaGGHbGaaiiEaaqabaGccqGH9aqpdaGabaqaauaa baqadmaaaeaacaWGJbGaey4kaSIaamiCaiGacshacaGGHbGaaiOBai abeA8aQbqaaiaaywW7caaMf8UaaGzbVdqaaiaadQgacqGH8aapcaWG QbWaaSbaaSqaaiGac2gacaGGHbGaaiiEaaqabaaakeaadaqadaqaai aadogacqGHRaWkcaWGWbGaciiDaiaacggacaGGUbGaeqOXdOgacaGL OaGaayzkaaGaamyzamaaCaaaleqabaWaaSaaaeaacaWGQbWaaSbaaW qaaiGac2gacaGGHbGaaiiEaaqabaWccqGHsislcaWGQbaabaGaam4A amaaBaaameaacaaIXaaabeaaaaaaaaGcbaaabaGaamOAamaaBaaale aaciGGTbGaaiyyaiaacIhaaeqaaOGaeyizImQaamOAaiabgsMiJkaa dQgadaWgaaWcbaGaamyDaaqabaaakeaadaqadaqaaiaadogacqGHRa WkcaWGWbGaciiDaiaacggacaGGUbGaeqOXdOgacaGLOaGaayzkaaGa aGjbVlaadkhaaeaaaeaacaWGQbGaeyOpa4JaamOAamaaBaaaleaaca WG1baabeaaaaaakiaawUhaaaaa@7A76@
ここで:
  • jmax = せん断応力の増加に影響を与える最大のせん断変位量
  • ju = 限界せん断変位
  • この時点よりもせん断変位を大きくしても、せん断応力には影響がなく、ju>jmax
  • k1 = 定数、r = 最大せん断比、1>r>0

τmaxが連続的な関数であるためには、次のような関係を保つ必要があります:

(5)
r= e j max j u k 1 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOCaiabg2 da9iaadwgadaahaaWcbeqaamaalaaabaGaamOAamaaBaaameaaciGG TbGaaiyyaiaacIhaaeqaaSGaeyOeI0IaamOAamaaBaaameaacaWG1b aabeaaaSqaaiaadUgadaWgaaadbaGaaGymaaqabaaaaaaaaaa@41FC@

したがって次のようになります:

(6)
k 1 = j max j u l n r MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbiqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4AamaaBa aaleaacaaIXaaabeaakiabg2da9maalaaabaGaamOAamaaBaaaleaa ciGGTbGaaiyyaiaacIhaaeqaaOGaeyOeI0IaamOAamaaBaaaleaaca WG1baabeaaaOqaaiaadYgacaWGHbGaamOBaiaaykW7caWGYbaaaaaa @4541@

次の図は、無次元せん断応力τ* と無次元せん断変位j* のプロットです。

ここで:

(7)
τ*= τ c+ptanφ ;j*= j k ; j max * = j max k =10; j u * = j u k =17;r=0.5 MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqiXdqNaai Okaiabg2da9maalaaabaGaeqiXdqhabaGaam4yaiabgUcaRiaadcha ciGG0bGaaiyyaiaac6gacqaHgpGAaaGaaGzbVlaacUdacaaMf8Uaam OAaiaacQcacqGH9aqpdaWcaaqaaiaadQgaaeaacaWGRbaaaiaaywW7 caGG7aGaaGzbVlaadQgadaqhaaWcbaGaciyBaiaacggacaGG4baaba GaaiOkaaaakiabg2da9maalaaabaGaamOAamaaBaaaleaaciGGTbGa aiyyaiaacIhaaeqaaaGcbaGaam4AaaaacqGH9aqpcaaIXaGaaGimai aaywW7caGG7aGaaGzbVlaadQgadaqhaaWcbaGaamyDaaqaaiaacQca aaGccqGH9aqpdaWcaaqaaiaadQgadaWgaaWcbaGaamyDaaqabaaake aacaWGRbaaaiabg2da9iaaigdacaaI3aGaaGzbVlaacUdacaaMf8Ua amOCaiabg2da9iaaicdacaGGUaGaaGynaaaa@714F@


図 1. 無次元せん断応力と無次元せん断変位の関係