目
1.

次土止めの種類と選択 ..................................................................................................................11.1 土止めの種類 ......................................................................................................................11.2 土止めの選択 ......................................................................................................................52. 土止めの設計 ...........................................................................................................................82.1 設計上の注意事項 ...............................................................................................................82.1.1 適用範囲 ......................................................................................................................82.1.2 土止め設計の項目と手順 ...............................................................................................82.2 土止めの設計 ....................................................................................................................103.

1

設計緒元の設定 ................................................................................................................ 102

親杭の根入れ長さの検討 .................................................................................................. 25

3

鋼矢板の根入れ長さの検討 ............................................................................................... 27

4

ヒービング、ボイリングに対する鋼矢板根入れ長さの検討 ............................................... 29

5親杭断面の算定 ................................................................................................................ 366横矢板断面の算定 ............................................................................................................ 38

7鋼矢板断面の算定 ............................................................................................................ 408軽量鋼矢板断面の算定 ...................................................................................................... 43

9矩形ライナープレート断面の算定 ..................................................................................... 45

10腹起しの設計 ................................................................................................................... 54

11切ばりの設計 ................................................................................................................... 57

12火打ちの設計 ................................................................................................................... 59

13中間支柱の設計 ................................................................................................................ 62

土止め支保工各部の構造と組立図 ............................................................................................66
3.1 土止め支保工の細部計画 ....................................................................................................66
3.2 土止め支保工各部の接合、取付図 .......................................................................................68
3.3 土止めの「組立図」 ..........................................................................................................68

4.

土止め施工の留意事項 ............................................................................................................73
4.1 土止め掘削の作業手順と施工上の留意事項 ..........................................................................734.1.1 土止め掘削の工事準備 .................................................................................................73
4.1.2 親杭横矢板土止め .......................................................................................................74
4.1.3 鋼矢板土止め ..............................................................................................................82
4.1.4 軽量鋼矢板土止め .......................................................................................................89

4.1.5 矩形ライナープレート土止め .......................................................................................95
4.2 鋼矢板打込みの作業手順と留意事項 .................................................................................100
4.2.1 バイブロハンマーを使用する場合 ..............................................................................100
4.2.2 油圧圧入工法（サイレントパイラー）を使用する場合 .................................................101
5.

土止めの点検と計測管理 .......................................................................................................104
5.1 土止めの点検 ..................................................................................................................104
5.1.1 点検の必要性 ............................................................................................................104
5.1.2 点検の要領 ...............................................................................................................104
5.1.3 補修・補強の要領 .....................................................................................................106
5.2 土止めの計測管理 ...........................................................................................................107
5.2.1 計測項目の選定 ........................................................................................................107
5.2.2 計 測 ......................................................................................................................107
5.2.3 計測結果の整理 ........................................................................................................109

6. 計 算 例 ...........................................................................................................................110
6.1 土止め設計計算(親杭横矢板) ............................................................................................110
6.1.1 設計諸元 ..................................................................................................................110
6.1.2 親杭の根入れ長さ .....................................................................................................110
6.1.3 親杭断面の設計(H-200 を仮定) ...................................................................................113
6.1.4 横矢板断面の設計 .....................................................................................................114
6.1.5 腹起しの設計 ............................................................................................................115
6.1.6 切ばりの設計 ............................................................................................................118
6.1.7 火打ちの設計 ............................................................................................................118
6.1.8 中間支柱の設計 ........................................................................................................119
6.2 土止め設計計算(鋼矢板) ...................................................................................................121
6.2.1 設計諸元 ..................................................................................................................121
6.2.2 鋼矢板の根入れ長さ ..................................................................................................121
6.2.3 鋼矢板断面の設計 .....................................................................................................124
6.3 土止め設計計算(軽量鋼矢板) ............................................................................................126
6.3.1 設計緒元 ..................................................................................................................126
6.3.2 軽量鋼矢板に作用する荷重 ........................................................................................1266.3.3 曲げモーメントの計算 ...............................................................................................126
6.3.4 断面強度の検討 ........................................................................................................127
6.3.5 ヒービング検討の計算例 ...........................................................................................127
6.4 土止め設計計算(矩形ライナープレート) ............................................................................129
6.4.1 設計緒元 ..................................................................................................................129
6.4.2 矩形ライナープレートに作用する荷重 ........................................................................129
6.4.3 断面力（曲げモーメント、軸力）の計算 .....................................................................130
6.4.4 断面強度の検討 ........................................................................................................133
6.4.5 補強リングの継手の計算 ...........................................................................................1357.

資 料 .................................................................................................................................141
7.1 土止め支保工材の形状・寸法 ...........................................................................................142
7.2 鋼矢板の形状寸法・断面性能 ...........................................................................................153
7.3 土止め主材（H 形鋼）の断面性能 .....................................................................................155
7.4 諸計算図表 .....................................................................................................................156
7.5 施工関連の諸図表 ...........................................................................................................167
7.5.1 杭打ハンマーの種類と適用性 .....................................................................................167
7.5.2 バイブロハンマー（主要機種）の仕様例 .....................................................................168
7.5.3 バイブロハンマーの適用（鋼矢板打込み） .................................................................169
7.5.4 バイブロハンマーの適用（鋼矢板引抜き） .................................................................169
7.5.5 地盤と鋼矢板の打込み可能長さ ..................................................................................169
7.5.6 油圧圧入（主要機種）の仕様例 ..................................................................................170
7.5.7 掘削機（バックホウ）の仕様例 ..................................................................................171
7.5.8 現場における地盤評価と N 値 .....................................................................................172
7.6 掘削・土止めに関連する諸法規 ..........................................................................................173