A method of preparing a site having a reduced swell potential of an expansive clayey soil at the site, wherein the expansive clayey soil comprises at least one expansive clay mineral, the proportion of the weight of the at least one expansive clay mineral relative to the total weight of the expansive clayey soil being PECM, the expansive clayey soil having a first water content and a cation exchange capacity (CEC) expressed in meq/100 g dry expansive clayey soil, the method comprising:
- (a) determining a second water content of a wetted expansive clayey soil to be formed by wetting the expansive clayey soil with water, the wetted expansive clayey soil having a reduced swell potential Sw(soil) that is no greater than a pre-set level T in accordance with a nano-level constitutive modeling based on the cation exchange capacity (CEC) of the expansive clayey soil and the second water content of the wetted expansive clayey soil as an initial water content (IWC),
- wherein the wetted expansive clayey soil comprises wetted at least one expansive clay mineral having the second water content and a swell potential Sw(ECM),
- wherein the second water content as the initial water content (IWC) is greater than the first water content but no greater than a final water content (FWC) of the at least one expansive clay mineral when the at least one expansive clay mineral reaches the swell potential, and produces a modified total cohesive energy density (TCEDm) of the wetted at least one expansive clay mineral calculated according to Equation (6) whether or not the expansive clayey soil further comprises at least one selected from the group consisting of calcite, gypsum, potassium chloride, calcium exchangeable cation, magnesium exchangeable cation, and potassium exchangeable cation:
- TCEDm=0.0625 (IWC)3−3.575 (IWC)2+10.5 (IWC)+2830+7100 (C/0.1)+5050 (G/0.2)+3010 (KCl/0.1)+Ca (500)+Mg (300)+K (100) (6)
- where TCEDm=modified TCED, C=Proportion of calcite weight relative to the total weight of the expansive clayey soil×PECM, G=Proportion of gypsum weight relative to the total weight of the expansive clayey soil×PECM, KCl=Proportion of potassium chloride weight relative to the total weight of the expansive clayey soil×PECM, Ca=Proportion of the number of calcium exchangeable cation relative to the total number of exchangeable cations in the expansive clayey soil, Mg=Proportion of the number of magnesium exchangeable cation relative to the total number of exchangeable cations in the expansive clayey soil, K=Proportion of the number of potassium exchangeable cation relative to the total number of exchangeable cations in the expansive clayey soil, IWC=initial water content,
- wherein the TCEDm of the wetted at least one expansive clay mineral results in Sw(ECM) calculated according to Equations (2), (3), and (5):
- IDD={−2E-15(TCEDm)4+5E-11(TCEDm)3−5E-07(TCEDm)2+0.0023(TCEDm)−1.5378}*1.85*(ABS(CEC−90)/90) (2)
- where IDD is initial dry density of the wetted at least one expansive clay mineral,
- FDD=−2E-22(TCEDm)6+5E-18(TCEDm)3−6E-14(TCEDm)4+3E-10(TCEDm)3−7E-07 (TCEDm)2+0.0005(TCEDm)+0.3747 (3)
- where FDD is final dry density of the wetted at least one expansive clay mineral when the wetted at least one expansive clay mineral reaches the swell potential Sw(ECM),
- Sw(ECM)(%)=(FDD−IDD)/FDD*100 (5);
- and
- wherein the reduced swell potential of the wetted expansive clayey soil Sw(soil) equals Sw(ECM)×PECM, and
- (b) installing pipes at the site in the expansive clayey soil having the first water content, wherein the pipes have injection points for injecting water into the expansive clayey soil having the first water content,
- (c) subgrade irrigating the expansive clayey soil having the first water content at the site with water to form the wetted expansive clayey soil having the second water content.