鈀築石門 The Rake Against Stone
八戒與沙僧連叫不出，獃子心焦，就使釘鈀築門。那門已此緊閉牢關，莫想能夠。被他七八鈀，築破門扇，裡面卻都是泥土石塊，高疊千層。沙僧見了道：「二哥，這怪物懼怕之甚，閉門不出，我和你且回上河崖，再與大哥計較去來。」八戒依言，徑轉東岸。八戒与沙僧连叫不出，呆子心焦，就使钉钯筑门。那门已此紧闭牢关，莫想能够。被他七八钯，筑破门扇，里面却都是泥土石块，高叠千层。沙僧见了道：「二哥，这怪物惧怕之甚，闭门不出，我和你且回上河崖，再与大哥计较去来。」八戒依言，径转东岸。
逐句解 Line by line
Eight Rules and Sha Monk called and called, but no one came out. The blockhead, growing anxious, set to and battered the gate with his rake.
連叫不出, calling and calling with nobody coming out. 獃子 keeps 子 as the toneless zi; 心焦, anxious, literally a scorched heart. The rake against the sealed gate is the last of the pilgrims' own methods.
But the gate was by now shut fast and barred tight, and there was no hope of forcing it.
那門 points, nà. 已此 is written for 以此, "by now." 莫想能夠, don't even think of managing it — the sentence concedes the failure before it describes the attempt.
He gave it seven or eight rake-blows and broke the gate-leaves open — but inside was nothing but mud and stones, piled up a thousand layers high.
門扇: 扇 is shàn, the word for a leaf of a door — the same character as a folding fan, and for the same reason. 都 dōu; 石塊 keeps 石 as shí. Breaking the gate reveals only the wall behind it: the demon meant what he said.
Seeing it, Sha Monk said: "Second brother, this monster's dread of us runs so deep that he has shut his gate and will not come out. You and I had better go back up to the river-cliff and take counsel again with Eldest Brother."
懼怕之甚: 甚 the intensifier shèn, "extremely." 計較, to talk it over and work something out. Sha Monk supplies the sober reading of the situation and the next move, as he has all chapter.
Eight Rules did as he said, and went straight back to the eastern bank.
依言, to act on what was said. The passage closes on the pilgrims walking away from a gate they cannot open — the failure that sends Wukong to the Southern Sea.
This is the mechanical proof of the passage before it. The demon said he would shut the gate and wait; here Bajie breaks the gate open and finds that shutting it was not a figure of speech. Behind the doors is a rampart of mud and stone 高疊千層, a thousand layers high. The pilgrims' most dependable instrument, the rake whose own poem two passages ago claimed it could level Mount Tai, splinters a wooden door and stops dead against a heap of dirt.
What the passage really marks is the exhaustion of the party's own resources. Reconnaissance, open battle, an ambush at the waterline, and now a direct assault on the gate — four methods, four failures, and the last one fails against something no amount of strength can usefully hit. Sha Monk's proposal that they go back and take counsel with Wukong is the admission that this is not a problem fighting can solve.