Table 7.

Significant analysis of the influence of six factors on undrained cohesion and moisture content of the clay.

Response variable	Source	Coefficient	$P$ value	Significance
$y_{c_U}$	Model		0.002	**
	$x_5$	0.615	0.000	**
	$x_5^2$	0.022	0.000	**
$y_{c_M}$	Model		0.001	**
	$x_1$	− 0.616	0.001	**
	$x_3$	− 0.120	0.012	*
	$x_4$	− 0.577	0.000	**
	$x_6$	− 0.373	0.001	**
	$x_1{x}_6$	0.017	0.002	**
$y_{c_L}$	Model		0.001	**
	$x_1$	− 0.542	0.001	**
	$x_3$	− 0.109	0.009	**
	$x_4$	− 0.511	0.000	**
	$x_5$	− 0.125	0.003	**
	$x_6$	− 0.337	0.001	**
	$x_1{x}_6$	0.016	0.001	**
$y_{{\omega }_U}$	Model		0.001	**
	$x_3$	0.053	0.030	*
	$x_4$	0.253	0.000	**
	$x_6$	− 0.185	0.005	**
	$x_6^2$	0.003	0.002	**
$y_{{\omega }_M}$	Model		0.000	**
	$x_4$	0.500	0.000	**
	$x_6$	− 0.128	0.050	*
	$x_6^2$	0.002	0.031	*
$y_{{\omega }_L}$	Model		0.000	**
	$x_4$	0.520	0.000	**
	$x_6^2$	0.003	0.021	*

where, “*” means generally significant difference at $P$ < 0.05 level; “**” means extremely significant difference at $P$ < 0.01 level; $F$ values of the model for undrained cohesion $y_{c_U}$, $y_{c_M}$, $y_{c_L}$ and moisture content $y_{{\omega }_U}$, $y_{{\omega }_M}$, $y_{{\omega }_L}$ were 5.703, 5.910, 6.090, 6.299, 11.719 and 9.940, respectively.